<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2023 Workiva-->
<!--r:91dc74a5-98f0-43a3-afac-b898d4f8e5c4,g:b72e1844-f9fe-40b3-b9a3-38ca5f5e1deb-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.incyte.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="incy-20230930.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_ede1abec-42f9-4a29-ae42-2868db0824e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_RevenuesAbstract_ede1abec-42f9-4a29-ae42-2868db0824e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_eeb5237b-a66f-492c-9dcc-eb15dd324d32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_ede1abec-42f9-4a29-ae42-2868db0824e1" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_eeb5237b-a66f-492c-9dcc-eb15dd324d32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_37db137c-4372-4bbc-9c14-f119205336e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:to="loc_us-gaap_CostOfRevenue_37db137c-4372-4bbc-9c14-f119205336e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_fa91328b-da2f-47f6-b315-1a2f3608e9f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_fa91328b-da2f-47f6-b315-1a2f3608e9f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_6e845b58-2020-43a2-989d-5b33a3b25b7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_6e845b58-2020-43a2-989d-5b33a3b25b7b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_932363c9-a005-4f86-a04c-8dc9cf28ad84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_932363c9-a005-4f86-a04c-8dc9cf28ad84" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CollaborationLossProfitSharingExpense_d62fe364-fe9a-4a09-8469-6eadcc18b34c" xlink:href="incy-20230930.xsd#incy_CollaborationLossProfitSharingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:to="loc_incy_CollaborationLossProfitSharingExpense_d62fe364-fe9a-4a09-8469-6eadcc18b34c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_72f71416-9cca-47bf-a711-2ec6fd145fac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_ce1180fa-2a7f-4e2f-b821-176afd76eef7" xlink:to="loc_us-gaap_CostsAndExpenses_72f71416-9cca-47bf-a711-2ec6fd145fac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_76301f44-f899-40af-88fe-8c3a37dc832f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_OperatingIncomeLoss_76301f44-f899-40af-88fe-8c3a37dc832f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_3a1445eb-1bf9-40a1-a6ec-91764e0cdca0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_3a1445eb-1bf9-40a1-a6ec-91764e0cdca0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_8e89e86c-f7eb-4f86-8df5-4c8c70927e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_InterestExpense_8e89e86c-f7eb-4f86-8df5-4c8c70927e7e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_b396430c-e2c8-43a7-afd2-ab0e0eb662c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_b396430c-e2c8-43a7-afd2-ab0e0eb662c0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_4bdfeae1-cc34-45a2-9f9c-83dd6f29c180" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_4bdfeae1-cc34-45a2-9f9c-83dd6f29c180" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_097d2d6f-e10d-4bbe-8ddf-67007c4ee8b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_097d2d6f-e10d-4bbe-8ddf-67007c4ee8b7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_d7af5f76-9fd2-47f0-88ee-8afe6c7e6d46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_NetIncomeLoss_d7af5f76-9fd2-47f0-88ee-8afe6c7e6d46" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_24712cb2-70e9-4414-8645-e00e7ff9482a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_EarningsPerShareAbstract_24712cb2-70e9-4414-8645-e00e7ff9482a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_7b87b97a-f587-488a-ae77-c3c6abfe0417" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_24712cb2-70e9-4414-8645-e00e7ff9482a" xlink:to="loc_us-gaap_EarningsPerShareBasic_7b87b97a-f587-488a-ae77-c3c6abfe0417" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_011f75f5-2bf7-4ac3-93f2-53a5aab62030" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_24712cb2-70e9-4414-8645-e00e7ff9482a" xlink:to="loc_us-gaap_EarningsPerShareDiluted_011f75f5-2bf7-4ac3-93f2-53a5aab62030" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_c9f5fee8-b836-4a7e-90fd-f6ee19f6904c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_c9f5fee8-b836-4a7e-90fd-f6ee19f6904c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_aa4f9a3f-b51e-4d5a-828a-228c95d51300" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_c9f5fee8-b836-4a7e-90fd-f6ee19f6904c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_aa4f9a3f-b51e-4d5a-828a-228c95d51300" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_bc34b906-bc22-48d7-ae11-9c1c810078c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_c9f5fee8-b836-4a7e-90fd-f6ee19f6904c" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_bc34b906-bc22-48d7-ae11-9c1c810078c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_1dde59a7-2c04-4be1-be65-523166e0a574" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_6d4b7cda-ae0b-4bfa-989a-19abf93def0b" xlink:to="loc_us-gaap_StatementTable_1dde59a7-2c04-4be1-be65-523166e0a574" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_6cc0918d-f86c-459c-a61c-47c052d9a020" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1dde59a7-2c04-4be1-be65-523166e0a574" xlink:to="loc_srt_ProductOrServiceAxis_6cc0918d-f86c-459c-a61c-47c052d9a020" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6cc0918d-f86c-459c-a61c-47c052d9a020_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_6cc0918d-f86c-459c-a61c-47c052d9a020" xlink:to="loc_srt_ProductsAndServicesDomain_6cc0918d-f86c-459c-a61c-47c052d9a020_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_61b73b8b-44b5-44d9-b47e-c44e3f26a0dd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_6cc0918d-f86c-459c-a61c-47c052d9a020" xlink:to="loc_srt_ProductsAndServicesDomain_61b73b8b-44b5-44d9-b47e-c44e3f26a0dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_266706f7-faa4-40fc-8ccf-90bcd515e60c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_61b73b8b-44b5-44d9-b47e-c44e3f26a0dd" xlink:to="loc_us-gaap_ProductMember_266706f7-faa4-40fc-8ccf-90bcd515e60c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RoyaltyMember_d083ed5f-b4aa-4b4a-8aee-88d772efa10f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RoyaltyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_61b73b8b-44b5-44d9-b47e-c44e3f26a0dd" xlink:to="loc_us-gaap_RoyaltyMember_d083ed5f-b4aa-4b4a-8aee-88d772efa10f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MilestoneRevenueMember_c3d669f1-e318-4a01-8b09-e43955f9aafc" xlink:href="incy-20230930.xsd#incy_MilestoneRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_61b73b8b-44b5-44d9-b47e-c44e3f26a0dd" xlink:to="loc_incy_MilestoneRevenueMember_c3d669f1-e318-4a01-8b09-e43955f9aafc" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="incy-20230930.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_abe77295-bc2e-412e-aed5-9239edcca94b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_abe77295-bc2e-412e-aed5-9239edcca94b" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_14dd55c6-9b61-4acc-a4f1-b203af18b091" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:to="loc_us-gaap_StockholdersEquity_14dd55c6-9b61-4acc-a4f1-b203af18b091" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_4235a1d8-3711-4df1-b07b-b2efb5b9cfff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_4235a1d8-3711-4df1-b07b-b2efb5b9cfff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_StockIssuedDuringPeriodValueStockOptionsAndRestrictedStockUnitsExercisedAndEmployeeStockPurchasePlan_2d125d5c-9409-4535-b279-6968cfdf0942" xlink:href="incy-20230930.xsd#incy_StockIssuedDuringPeriodValueStockOptionsAndRestrictedStockUnitsExercisedAndEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:to="loc_incy_StockIssuedDuringPeriodValueStockOptionsAndRestrictedStockUnitsExercisedAndEmployeeStockPurchasePlan_2d125d5c-9409-4535-b279-6968cfdf0942" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForServices_0a1dc68a-f703-4d9a-b19e-9fb08bd91be6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueIssuedForServices_0a1dc68a-f703-4d9a-b19e-9fb08bd91be6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_ea387e88-8927-4948-b53c-2696bf3859f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_ea387e88-8927-4948-b53c-2696bf3859f5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_6f4709b6-227b-4419-aca1-63f7dff1924d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_6f4709b6-227b-4419-aca1-63f7dff1924d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_377e05b1-9e48-48f5-931a-cfd52bd0f305" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_b23267dd-8792-4a61-a129-15452db1b7a7" xlink:to="loc_us-gaap_NetIncomeLoss_377e05b1-9e48-48f5-931a-cfd52bd0f305" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_75c4415a-d092-4725-83a6-df8718efc3cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_978bebaf-8113-4aeb-acb9-a4ea50d354b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_abe77295-bc2e-412e-aed5-9239edcca94b" xlink:to="loc_us-gaap_StatementTable_978bebaf-8113-4aeb-acb9-a4ea50d354b5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_d1fcf0a9-b7c0-4425-aef9-37d5fefeaac5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_978bebaf-8113-4aeb-acb9-a4ea50d354b5" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_d1fcf0a9-b7c0-4425-aef9-37d5fefeaac5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_d1fcf0a9-b7c0-4425-aef9-37d5fefeaac5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d1fcf0a9-b7c0-4425-aef9-37d5fefeaac5" xlink:to="loc_us-gaap_EquityComponentDomain_d1fcf0a9-b7c0-4425-aef9-37d5fefeaac5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_b211dbd2-d359-4d9a-aba7-99b61af399d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d1fcf0a9-b7c0-4425-aef9-37d5fefeaac5" xlink:to="loc_us-gaap_EquityComponentDomain_b211dbd2-d359-4d9a-aba7-99b61af399d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_3e8b9d95-67c3-44e4-8095-e61223e2499a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_b211dbd2-d359-4d9a-aba7-99b61af399d5" xlink:to="loc_us-gaap_CommonStockMember_3e8b9d95-67c3-44e4-8095-e61223e2499a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_35cc1781-f853-4726-8bf4-6a32cfe2381f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_b211dbd2-d359-4d9a-aba7-99b61af399d5" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_35cc1781-f853-4726-8bf4-6a32cfe2381f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2bd8b4ef-1858-403d-bb99-c1f7a7bb8881" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_b211dbd2-d359-4d9a-aba7-99b61af399d5" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2bd8b4ef-1858-403d-bb99-c1f7a7bb8881" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_1189ff0a-4204-4e90-b7a4-3abfb1449e15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_b211dbd2-d359-4d9a-aba7-99b61af399d5" xlink:to="loc_us-gaap_RetainedEarningsMember_1189ff0a-4204-4e90-b7a4-3abfb1449e15" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/SummaryofSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#SummaryofSignificantAccountingPoliciesDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/SummaryofSignificantAccountingPoliciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b1164bc2-f81b-4107-a3a2-e0a3af4b89aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_03d09306-ce52-4a86-9b4f-32bd5a164309" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b1164bc2-f81b-4107-a3a2-e0a3af4b89aa" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_03d09306-ce52-4a86-9b4f-32bd5a164309" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_bf193da2-eeb3-4b48-8a7d-6f7946df690a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b1164bc2-f81b-4107-a3a2-e0a3af4b89aa" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_bf193da2-eeb3-4b48-8a7d-6f7946df690a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_e2fc610d-c51c-463d-8684-fb3335e579d3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_bf193da2-eeb3-4b48-8a7d-6f7946df690a" xlink:to="loc_srt_ProductOrServiceAxis_e2fc610d-c51c-463d-8684-fb3335e579d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e2fc610d-c51c-463d-8684-fb3335e579d3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_e2fc610d-c51c-463d-8684-fb3335e579d3" xlink:to="loc_srt_ProductsAndServicesDomain_e2fc610d-c51c-463d-8684-fb3335e579d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_687bdf2d-4ef4-42c3-ad93-ccb4b8f5d474" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_e2fc610d-c51c-463d-8684-fb3335e579d3" xlink:to="loc_srt_ProductsAndServicesDomain_687bdf2d-4ef4-42c3-ad93-ccb4b8f5d474" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ICLUSIGMember_c4c7eb07-3353-436f-926e-7e185e50cab8" xlink:href="incy-20230930.xsd#incy_ICLUSIGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_687bdf2d-4ef4-42c3-ad93-ccb4b8f5d474" xlink:to="loc_incy_ICLUSIGMember_c4c7eb07-3353-436f-926e-7e185e50cab8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_2d2f9d3c-28c8-4c33-ac3e-ff3bbb114dcc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_bf193da2-eeb3-4b48-8a7d-6f7946df690a" xlink:to="loc_srt_RangeAxis_2d2f9d3c-28c8-4c33-ac3e-ff3bbb114dcc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_2d2f9d3c-28c8-4c33-ac3e-ff3bbb114dcc_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_2d2f9d3c-28c8-4c33-ac3e-ff3bbb114dcc" xlink:to="loc_srt_RangeMember_2d2f9d3c-28c8-4c33-ac3e-ff3bbb114dcc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_81b593ea-c5f7-4e6e-8df3-37e03f7d0151" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_2d2f9d3c-28c8-4c33-ac3e-ff3bbb114dcc" xlink:to="loc_srt_RangeMember_81b593ea-c5f7-4e6e-8df3-37e03f7d0151" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_61ae8689-d97c-42d8-be6a-513eb6340c24" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_81b593ea-c5f7-4e6e-8df3-37e03f7d0151" xlink:to="loc_srt_MinimumMember_61ae8689-d97c-42d8-be6a-513eb6340c24" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_1264417c-5cbb-4ebc-b4dd-911a46cd0975" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_81b593ea-c5f7-4e6e-8df3-37e03f7d0151" xlink:to="loc_srt_MaximumMember_1264417c-5cbb-4ebc-b4dd-911a46cd0975" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/RevenuesDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#RevenuesDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/RevenuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_35b4b453-464a-43ad-8207-948cfa04d3c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_819d7355-08a7-4d53-8ae8-aebfd4d9ed0d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_35b4b453-464a-43ad-8207-948cfa04d3c4" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_819d7355-08a7-4d53-8ae8-aebfd4d9ed0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_3d99634a-11a7-41f4-acce-43394d7fe9a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_35b4b453-464a-43ad-8207-948cfa04d3c4" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_3d99634a-11a7-41f4-acce-43394d7fe9a8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_11e2eb90-23bc-4f14-8efa-41efe91ba21d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_3d99634a-11a7-41f4-acce-43394d7fe9a8" xlink:to="loc_srt_ProductOrServiceAxis_11e2eb90-23bc-4f14-8efa-41efe91ba21d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_11e2eb90-23bc-4f14-8efa-41efe91ba21d_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_11e2eb90-23bc-4f14-8efa-41efe91ba21d" xlink:to="loc_srt_ProductsAndServicesDomain_11e2eb90-23bc-4f14-8efa-41efe91ba21d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b5c00f04-9f59-4b31-a021-ded148579ada" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_11e2eb90-23bc-4f14-8efa-41efe91ba21d" xlink:to="loc_srt_ProductsAndServicesDomain_b5c00f04-9f59-4b31-a021-ded148579ada" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b5c00f04-9f59-4b31-a021-ded148579ada" xlink:to="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_JAKAFIMember_292fe570-7800-4e33-877b-c08a0d78a6ec" xlink:href="incy-20230930.xsd#incy_JAKAFIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:to="loc_incy_JAKAFIMember_292fe570-7800-4e33-877b-c08a0d78a6ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_OpzeluraMember_39bb60cc-db11-457c-a3b8-9701af2cb43e" xlink:href="incy-20230930.xsd#incy_OpzeluraMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:to="loc_incy_OpzeluraMember_39bb60cc-db11-457c-a3b8-9701af2cb43e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ICLUSIGMember_1d7a7e5c-3868-4dcc-a730-549603dc02d7" xlink:href="incy-20230930.xsd#incy_ICLUSIGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:to="loc_incy_ICLUSIGMember_1d7a7e5c-3868-4dcc-a730-549603dc02d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_PemazyreMember_6576743a-ba94-42b7-b360-880f3890a565" xlink:href="incy-20230930.xsd#incy_PemazyreMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:to="loc_incy_PemazyreMember_6576743a-ba94-42b7-b360-880f3890a565" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MINJUVIMember_b8365f16-ada7-4e49-8a70-f52b43c45310" xlink:href="incy-20230930.xsd#incy_MINJUVIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:to="loc_incy_MINJUVIMember_b8365f16-ada7-4e49-8a70-f52b43c45310" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ZYNYZMember_dc7c3f1b-0bfa-4207-adbc-8c6132ca1452" xlink:href="incy-20230930.xsd#incy_ZYNYZMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_7cdf30bb-1c78-45ef-b762-7926ace98f98" xlink:to="loc_incy_ZYNYZMember_dc7c3f1b-0bfa-4207-adbc-8c6132ca1452" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RoyaltyMember_2c6da7d8-0145-4a5d-bb46-2af4f759f9ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RoyaltyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b5c00f04-9f59-4b31-a021-ded148579ada" xlink:to="loc_us-gaap_RoyaltyMember_2c6da7d8-0145-4a5d-bb46-2af4f759f9ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_JakaviRoyaltyRevenuesMember_afbe5ac8-0cb8-4965-8c9a-61cdd78b1df1" xlink:href="incy-20230930.xsd#incy_JakaviRoyaltyRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RoyaltyMember_2c6da7d8-0145-4a5d-bb46-2af4f759f9ac" xlink:to="loc_incy_JakaviRoyaltyRevenuesMember_afbe5ac8-0cb8-4965-8c9a-61cdd78b1df1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_OlumiantRoyaltyMember_644b71ef-b3b0-4f24-8675-595da4014908" xlink:href="incy-20230930.xsd#incy_OlumiantRoyaltyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RoyaltyMember_2c6da7d8-0145-4a5d-bb46-2af4f759f9ac" xlink:to="loc_incy_OlumiantRoyaltyMember_644b71ef-b3b0-4f24-8675-595da4014908" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_TabrectaRoyaltyRevenuesMember_f5d324a6-49c8-4348-afd3-243bfccf241e" xlink:href="incy-20230930.xsd#incy_TabrectaRoyaltyRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RoyaltyMember_2c6da7d8-0145-4a5d-bb46-2af4f759f9ac" xlink:to="loc_incy_TabrectaRoyaltyRevenuesMember_f5d324a6-49c8-4348-afd3-243bfccf241e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_PEMAZYRERoyaltyRevenuesMember_2efe369b-cba7-4090-8696-4c559734a0fd" xlink:href="incy-20230930.xsd#incy_PEMAZYRERoyaltyRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RoyaltyMember_2c6da7d8-0145-4a5d-bb46-2af4f759f9ac" xlink:to="loc_incy_PEMAZYRERoyaltyRevenuesMember_2efe369b-cba7-4090-8696-4c559734a0fd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MilestoneAndContractRevenueMember_213cefbf-4dcd-4f2d-afb5-9113dad93474" xlink:href="incy-20230930.xsd#incy_MilestoneAndContractRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b5c00f04-9f59-4b31-a021-ded148579ada" xlink:to="loc_incy_MilestoneAndContractRevenueMember_213cefbf-4dcd-4f2d-afb5-9113dad93474" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/FairValueofFinancialInstrumentsMarketablesecuritiesportfolioDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#FairValueofFinancialInstrumentsMarketablesecuritiesportfolioDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/FairValueofFinancialInstrumentsMarketablesecuritiesportfolioDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_d451474f-0101-4464-97ec-e7947cd4180b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_0db3d266-d2c3-4857-9742-915f4923c4e5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_d451474f-0101-4464-97ec-e7947cd4180b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_0db3d266-d2c3-4857-9742-915f4923c4e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainLossBeforeTax_ddea86ab-bb13-4af9-9b4a-cdb985f39964" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_d451474f-0101-4464-97ec-e7947cd4180b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainLossBeforeTax_ddea86ab-bb13-4af9-9b4a-cdb985f39964" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_cc011023-a7e4-4bf8-a1c8-cba7612770c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_d451474f-0101-4464-97ec-e7947cd4180b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_cc011023-a7e4-4bf8-a1c8-cba7612770c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_ba151212-ed61-420b-a814-bc7ea6339e45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_d451474f-0101-4464-97ec-e7947cd4180b" xlink:to="loc_us-gaap_DebtInstrumentTerm_ba151212-ed61-420b-a814-bc7ea6339e45" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_8e590f7b-ca12-4ad4-932d-c72edf6e142c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_d451474f-0101-4464-97ec-e7947cd4180b" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_8e590f7b-ca12-4ad4-932d-c72edf6e142c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_7be712b3-78af-43e8-8243-e3c98afcafbd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_8e590f7b-ca12-4ad4-932d-c72edf6e142c" xlink:to="loc_us-gaap_FinancialInstrumentAxis_7be712b3-78af-43e8-8243-e3c98afcafbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7be712b3-78af-43e8-8243-e3c98afcafbd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7be712b3-78af-43e8-8243-e3c98afcafbd" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7be712b3-78af-43e8-8243-e3c98afcafbd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_00ded21e-8810-44e6-bc9a-915b2850dc33" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7be712b3-78af-43e8-8243-e3c98afcafbd" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_00ded21e-8810-44e6-bc9a-915b2850dc33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CorporateAndGovernmentDebtSecuritiesMember_451208d4-82eb-4b66-aefd-05362f105bd2" xlink:href="incy-20230930.xsd#incy_CorporateAndGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_00ded21e-8810-44e6-bc9a-915b2850dc33" xlink:to="loc_incy_CorporateAndGovernmentDebtSecuritiesMember_451208d4-82eb-4b66-aefd-05362f105bd2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_707760ac-df4c-4198-ac38-8c53ba4afea5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_8e590f7b-ca12-4ad4-932d-c72edf6e142c" xlink:to="loc_srt_RangeAxis_707760ac-df4c-4198-ac38-8c53ba4afea5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_707760ac-df4c-4198-ac38-8c53ba4afea5_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_707760ac-df4c-4198-ac38-8c53ba4afea5" xlink:to="loc_srt_RangeMember_707760ac-df4c-4198-ac38-8c53ba4afea5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0a596908-5606-46e0-83fd-3fefefc17c44" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_707760ac-df4c-4198-ac38-8c53ba4afea5" xlink:to="loc_srt_RangeMember_0a596908-5606-46e0-83fd-3fefefc17c44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_32ce30ec-d750-412a-9245-2260b347357e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0a596908-5606-46e0-83fd-3fefefc17c44" xlink:to="loc_srt_MinimumMember_32ce30ec-d750-412a-9245-2260b347357e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_91d58335-e72e-42b1-bd91-b814a205e265" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0a596908-5606-46e0-83fd-3fefefc17c44" xlink:to="loc_srt_MaximumMember_91d58335-e72e-42b1-bd91-b814a205e265" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/FairValueofFinancialInstrumentsAssetsmeasuredonarecurringbasisDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#FairValueofFinancialInstrumentsAssetsmeasuredonarecurringbasisDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/FairValueofFinancialInstrumentsAssetsmeasuredonarecurringbasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f182fbd4-3ab8-4979-902e-360cc4027f0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_9f1d6de9-4a25-4492-8b8c-4c01b049d030" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f182fbd4-3ab8-4979-902e-360cc4027f0b" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_9f1d6de9-4a25-4492-8b8c-4c01b049d030" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_9018fe9c-ad8c-441a-a605-dfd39a4a078c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f182fbd4-3ab8-4979-902e-360cc4027f0b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_9018fe9c-ad8c-441a-a605-dfd39a4a078c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermInvestments_1311de0e-c5bf-4f0f-bb67-ec2f2c16d5c8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f182fbd4-3ab8-4979-902e-360cc4027f0b" xlink:to="loc_us-gaap_LongTermInvestments_1311de0e-c5bf-4f0f-bb67-ec2f2c16d5c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_d97f3043-9aa7-4d95-9836-502047f8c423" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f182fbd4-3ab8-4979-902e-360cc4027f0b" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_d97f3043-9aa7-4d95-9836-502047f8c423" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7501c4ea-29aa-41b0-a90c-3c651664c87b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f182fbd4-3ab8-4979-902e-360cc4027f0b" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7501c4ea-29aa-41b0-a90c-3c651664c87b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_815e45cc-0124-483e-be17-d0ac35abb254" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7501c4ea-29aa-41b0-a90c-3c651664c87b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_815e45cc-0124-483e-be17-d0ac35abb254" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_815e45cc-0124-483e-be17-d0ac35abb254_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_815e45cc-0124-483e-be17-d0ac35abb254" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_815e45cc-0124-483e-be17-d0ac35abb254_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_379cd5fe-c3bc-4e8b-a518-31dda82bc4c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_815e45cc-0124-483e-be17-d0ac35abb254" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_379cd5fe-c3bc-4e8b-a518-31dda82bc4c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_b00d1b37-43c6-42e7-a8f7-3ea29d54d705" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_379cd5fe-c3bc-4e8b-a518-31dda82bc4c2" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_b00d1b37-43c6-42e7-a8f7-3ea29d54d705" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_8545c739-5952-4310-83c0-cde358226d1c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_379cd5fe-c3bc-4e8b-a518-31dda82bc4c2" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_8545c739-5952-4310-83c0-cde358226d1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_61d84a28-2609-4e75-be2d-892ada75c50c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_379cd5fe-c3bc-4e8b-a518-31dda82bc4c2" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_61d84a28-2609-4e75-be2d-892ada75c50c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c7caba7f-3121-4c69-a72e-0256b6ef91f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7501c4ea-29aa-41b0-a90c-3c651664c87b" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c7caba7f-3121-4c69-a72e-0256b6ef91f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_c7caba7f-3121-4c69-a72e-0256b6ef91f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c7caba7f-3121-4c69-a72e-0256b6ef91f8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_c7caba7f-3121-4c69-a72e-0256b6ef91f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_8ebd583b-f3a6-4fc1-be60-5c726893e91c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_c7caba7f-3121-4c69-a72e-0256b6ef91f8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_8ebd583b-f3a6-4fc1-be60-5c726893e91c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_3fd4006f-f358-4e0a-8f1c-27e1881ff8a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_8ebd583b-f3a6-4fc1-be60-5c726893e91c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_3fd4006f-f358-4e0a-8f1c-27e1881ff8a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_9d87a5f2-eb07-47ce-82d3-f646d378f4f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7501c4ea-29aa-41b0-a90c-3c651664c87b" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_9d87a5f2-eb07-47ce-82d3-f646d378f4f9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_9d87a5f2-eb07-47ce-82d3-f646d378f4f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_9d87a5f2-eb07-47ce-82d3-f646d378f4f9" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_9d87a5f2-eb07-47ce-82d3-f646d378f4f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4ddd0429-92a9-4d79-99d7-c1922d3099c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_9d87a5f2-eb07-47ce-82d3-f646d378f4f9" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4ddd0429-92a9-4d79-99d7-c1922d3099c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a45c2fe2-5f14-4be6-b07e-acfe16999aac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_4ddd0429-92a9-4d79-99d7-c1922d3099c3" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a45c2fe2-5f14-4be6-b07e-acfe16999aac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_a81fc9e2-f6f3-4ddb-8bf6-16b38aca81c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a45c2fe2-5f14-4be6-b07e-acfe16999aac" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_a81fc9e2-f6f3-4ddb-8bf6-16b38aca81c2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/FairValueofFinancialInstrumentsLiabilitiesmeasuredonarecurringbasisDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#FairValueofFinancialInstrumentsLiabilitiesmeasuredonarecurringbasisDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/FairValueofFinancialInstrumentsLiabilitiesmeasuredonarecurringbasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_38900ca3-367b-4ac7-8728-2b5fea554d7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_c5819120-e9d9-49ad-b72f-5c74ad229530" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_38900ca3-367b-4ac7-8728-2b5fea554d7d" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_c5819120-e9d9-49ad-b72f-5c74ad229530" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_49dda5c6-b33e-4471-b8aa-1d844459904f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_38900ca3-367b-4ac7-8728-2b5fea554d7d" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_49dda5c6-b33e-4471-b8aa-1d844459904f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_cd22c6a9-1ec9-4220-8269-f8bcf5a214c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_38900ca3-367b-4ac7-8728-2b5fea554d7d" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_cd22c6a9-1ec9-4220-8269-f8bcf5a214c9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a3f35ed4-f3be-4d07-bd1d-1d5a6df87264" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_cd22c6a9-1ec9-4220-8269-f8bcf5a214c9" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a3f35ed4-f3be-4d07-bd1d-1d5a6df87264" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a3f35ed4-f3be-4d07-bd1d-1d5a6df87264_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a3f35ed4-f3be-4d07-bd1d-1d5a6df87264" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a3f35ed4-f3be-4d07-bd1d-1d5a6df87264_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7eabf5a6-f6e8-4f11-bf00-999c8135bf51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a3f35ed4-f3be-4d07-bd1d-1d5a6df87264" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7eabf5a6-f6e8-4f11-bf00-999c8135bf51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_6947cc3c-c8d8-4678-9bae-6f1ec12b2778" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7eabf5a6-f6e8-4f11-bf00-999c8135bf51" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_6947cc3c-c8d8-4678-9bae-6f1ec12b2778" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_55a79403-d0b9-42e0-8ee6-ff859034cffa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7eabf5a6-f6e8-4f11-bf00-999c8135bf51" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_55a79403-d0b9-42e0-8ee6-ff859034cffa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_5db4280e-d5d9-4ce4-88d8-010be42034d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7eabf5a6-f6e8-4f11-bf00-999c8135bf51" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_5db4280e-d5d9-4ce4-88d8-010be42034d4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3c3d55f2-65c8-4093-892a-242d367b52be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_cd22c6a9-1ec9-4220-8269-f8bcf5a214c9" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3c3d55f2-65c8-4093-892a-242d367b52be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3c3d55f2-65c8-4093-892a-242d367b52be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3c3d55f2-65c8-4093-892a-242d367b52be" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3c3d55f2-65c8-4093-892a-242d367b52be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_4d0fd4e2-b9aa-45fe-bae9-5643eebe4a4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3c3d55f2-65c8-4093-892a-242d367b52be" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_4d0fd4e2-b9aa-45fe-bae9-5643eebe4a4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_a9d195a9-8871-42f2-baa7-b7a00a95ab80" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_4d0fd4e2-b9aa-45fe-bae9-5643eebe4a4c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_a9d195a9-8871-42f2-baa7-b7a00a95ab80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_c89aea54-656f-43c3-8a5e-06fd9453d454" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_cd22c6a9-1ec9-4220-8269-f8bcf5a214c9" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_c89aea54-656f-43c3-8a5e-06fd9453d454" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c89aea54-656f-43c3-8a5e-06fd9453d454_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_c89aea54-656f-43c3-8a5e-06fd9453d454" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c89aea54-656f-43c3-8a5e-06fd9453d454_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_427cc93d-5922-4d88-936e-56a22cd71a36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_c89aea54-656f-43c3-8a5e-06fd9453d454" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_427cc93d-5922-4d88-936e-56a22cd71a36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_572ae8a1-d634-49cf-ba55-465b9abc46b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_427cc93d-5922-4d88-936e-56a22cd71a36" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_572ae8a1-d634-49cf-ba55-465b9abc46b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_969e8ef7-0c52-4cd6-bcd2-16db39beb675" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_572ae8a1-d634-49cf-ba55-465b9abc46b1" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_969e8ef7-0c52-4cd6-bcd2-16db39beb675" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/FairValueofFinancialInstrumentsLevel3liabilitiesDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#FairValueofFinancialInstrumentsLevel3liabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/FairValueofFinancialInstrumentsLevel3liabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f96cff55-5600-4321-9cb3-0b1e7d5d3aea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_984e9f82-555b-466e-9412-a0d22fd48466" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f96cff55-5600-4321-9cb3-0b1e7d5d3aea" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_984e9f82-555b-466e-9412-a0d22fd48466" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_cabd2599-fbb6-444a-895f-5ebe52728db9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_984e9f82-555b-466e-9412-a0d22fd48466" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_cabd2599-fbb6-444a-895f-5ebe52728db9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiabilityConsiderationEarned_bd61baaa-bd59-43ea-8430-14ac1604c7de" xlink:href="incy-20230930.xsd#incy_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiabilityConsiderationEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_984e9f82-555b-466e-9412-a0d22fd48466" xlink:to="loc_incy_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiabilityConsiderationEarned_bd61baaa-bd59-43ea-8430-14ac1604c7de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_d27ef597-94e2-41d6-81e3-1651f44ae287" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_984e9f82-555b-466e-9412-a0d22fd48466" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_d27ef597-94e2-41d6-81e3-1651f44ae287" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_af77e22d-67cf-41df-b6ed-a631f43fe3c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_984e9f82-555b-466e-9412-a0d22fd48466" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_af77e22d-67cf-41df-b6ed-a631f43fe3c4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_1e4461a3-35d4-4ccd-a92a-6f3a683a22af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde265f6-5593-44d1-9ee3-251133de563f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_f96cff55-5600-4321-9cb3-0b1e7d5d3aea" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde265f6-5593-44d1-9ee3-251133de563f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_66ca145a-f393-47dd-93c3-ba3c577b0ccb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde265f6-5593-44d1-9ee3-251133de563f" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_66ca145a-f393-47dd-93c3-ba3c577b0ccb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_66ca145a-f393-47dd-93c3-ba3c577b0ccb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_66ca145a-f393-47dd-93c3-ba3c577b0ccb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_66ca145a-f393-47dd-93c3-ba3c577b0ccb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_970ddc95-27ae-4d59-92e8-22f95ea1e28d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_66ca145a-f393-47dd-93c3-ba3c577b0ccb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_970ddc95-27ae-4d59-92e8-22f95ea1e28d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_30d8655f-4a6d-4ad2-a3bc-43e4b971e9ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_970ddc95-27ae-4d59-92e8-22f95ea1e28d" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_30d8655f-4a6d-4ad2-a3bc-43e4b971e9ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_9e6e64f2-1b87-4bd1-beca-4fca0cce98e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_bde265f6-5593-44d1-9ee3-251133de563f" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_9e6e64f2-1b87-4bd1-beca-4fca0cce98e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_9e6e64f2-1b87-4bd1-beca-4fca0cce98e2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_9e6e64f2-1b87-4bd1-beca-4fca0cce98e2" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_9e6e64f2-1b87-4bd1-beca-4fca0cce98e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_538bf0d9-907a-4922-b588-c8bfc0846cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_9e6e64f2-1b87-4bd1-beca-4fca0cce98e2" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_538bf0d9-907a-4922-b588-c8bfc0846cfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_1d99cb4b-85cc-4f61-aec9-18eec0f8e4d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_538bf0d9-907a-4922-b588-c8bfc0846cfe" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_1d99cb4b-85cc-4f61-aec9-18eec0f8e4d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_82f3e485-1989-419c-bda5-850b2dabc3b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_1d99cb4b-85cc-4f61-aec9-18eec0f8e4d6" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_82f3e485-1989-419c-bda5-850b2dabc3b1" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/FairValueofFinancialInstrumentsNarrativeDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#FairValueofFinancialInstrumentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/FairValueofFinancialInstrumentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bb89ea47-da31-4665-abec-28469924c2b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_FairValueInputsCashFlowsEstimatedPeriod_71489023-948f-4607-aa19-fcec2578c328" xlink:href="incy-20230930.xsd#incy_FairValueInputsCashFlowsEstimatedPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bb89ea47-da31-4665-abec-28469924c2b6" xlink:to="loc_incy_FairValueInputsCashFlowsEstimatedPeriod_71489023-948f-4607-aa19-fcec2578c328" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput_6a6cac2f-752d-4ae8-83f1-0f3f15098e14" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bb89ea47-da31-4665-abec-28469924c2b6" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput_6a6cac2f-752d-4ae8-83f1-0f3f15098e14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiabilityConsiderationEarned_1dd4862a-9a3a-4991-aac9-c7d31c81922e" xlink:href="incy-20230930.xsd#incy_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiabilityConsiderationEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bb89ea47-da31-4665-abec-28469924c2b6" xlink:to="loc_incy_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiabilityConsiderationEarned_1dd4862a-9a3a-4991-aac9-c7d31c81922e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e36c6f1-bbf7-4fb1-b52d-70e744c5c490" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_bb89ea47-da31-4665-abec-28469924c2b6" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e36c6f1-bbf7-4fb1-b52d-70e744c5c490" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_9c504b3d-5946-47c1-a9ab-eab5599d8091" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e36c6f1-bbf7-4fb1-b52d-70e744c5c490" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_9c504b3d-5946-47c1-a9ab-eab5599d8091" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9c504b3d-5946-47c1-a9ab-eab5599d8091_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9c504b3d-5946-47c1-a9ab-eab5599d8091" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9c504b3d-5946-47c1-a9ab-eab5599d8091_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_13c08d75-ebf1-4776-8104-ed339fafe82e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9c504b3d-5946-47c1-a9ab-eab5599d8091" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_13c08d75-ebf1-4776-8104-ed339fafe82e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AriadPharmaceuticalsMember_dfb20e5e-caf2-4104-88b0-1522cc7bdb31" xlink:href="incy-20230930.xsd#incy_AriadPharmaceuticalsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_13c08d75-ebf1-4776-8104-ed339fafe82e" xlink:to="loc_incy_AriadPharmaceuticalsMember_dfb20e5e-caf2-4104-88b0-1522cc7bdb31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_86b70786-b173-4866-ba09-c30e471f1a5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e36c6f1-bbf7-4fb1-b52d-70e744c5c490" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_86b70786-b173-4866-ba09-c30e471f1a5d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_86b70786-b173-4866-ba09-c30e471f1a5d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_86b70786-b173-4866-ba09-c30e471f1a5d" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_86b70786-b173-4866-ba09-c30e471f1a5d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0c056806-a451-4c8b-b981-1a8d9c78ec1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_86b70786-b173-4866-ba09-c30e471f1a5d" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0c056806-a451-4c8b-b981-1a8d9c78ec1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityMember_9b906ddd-6670-45c6-80f9-2cceb17ba25c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0c056806-a451-4c8b-b981-1a8d9c78ec1a" xlink:to="loc_us-gaap_LiabilityMember_9b906ddd-6670-45c6-80f9-2cceb17ba25c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_fcfdd882-801b-4994-9f58-abbe75642102" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e36c6f1-bbf7-4fb1-b52d-70e744c5c490" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_fcfdd882-801b-4994-9f58-abbe75642102" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_fcfdd882-801b-4994-9f58-abbe75642102_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_fcfdd882-801b-4994-9f58-abbe75642102" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_fcfdd882-801b-4994-9f58-abbe75642102_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_4c0afa9a-e2a8-44c2-abf9-7fb0b0e206cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_fcfdd882-801b-4994-9f58-abbe75642102" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_4c0afa9a-e2a8-44c2-abf9-7fb0b0e206cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_3d7c3e5a-325e-46a0-856b-0b5bc9d4fa91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_4c0afa9a-e2a8-44c2-abf9-7fb0b0e206cc" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_3d7c3e5a-325e-46a0-856b-0b5bc9d4fa91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_26b1dacd-e415-4c98-8457-8473b8c99f31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5e36c6f1-bbf7-4fb1-b52d-70e744c5c490" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_26b1dacd-e415-4c98-8457-8473b8c99f31" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_26b1dacd-e415-4c98-8457-8473b8c99f31_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_26b1dacd-e415-4c98-8457-8473b8c99f31" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_26b1dacd-e415-4c98-8457-8473b8c99f31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_84951048-e31f-47f8-b054-6f647af993e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_26b1dacd-e415-4c98-8457-8473b8c99f31" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_84951048-e31f-47f8-b054-6f647af993e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AccruedAndOtherCurrentLiabilitiesMember_efe26fa5-7bd7-444b-96a4-169fb0952764" xlink:href="incy-20230930.xsd#incy_AccruedAndOtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_84951048-e31f-47f8-b054-6f647af993e9" xlink:to="loc_incy_AccruedAndOtherCurrentLiabilitiesMember_efe26fa5-7bd7-444b-96a4-169fb0952764" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/ConcentrationofCreditRiskandCurrentExpectedCreditLossesDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#ConcentrationofCreditRiskandCurrentExpectedCreditLossesDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/ConcentrationofCreditRiskandCurrentExpectedCreditLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_b5663136-b431-41ed-a3d2-1312fb52b50c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_d6bb56c1-25c7-43c7-8a6b-72069be7eb6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_b5663136-b431-41ed-a3d2-1312fb52b50c" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_d6bb56c1-25c7-43c7-8a6b-72069be7eb6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_3ba882c9-1ec4-46a5-852a-50912f9bcdf3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_b5663136-b431-41ed-a3d2-1312fb52b50c" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_3ba882c9-1ec4-46a5-852a-50912f9bcdf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_4ea2a0e3-96ed-411d-9448-80c60e99b055" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_b5663136-b431-41ed-a3d2-1312fb52b50c" xlink:to="loc_us-gaap_ConcentrationRiskTable_4ea2a0e3-96ed-411d-9448-80c60e99b055" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_bf8d4373-e826-4fb7-8c84-eb99857b07db" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_4ea2a0e3-96ed-411d-9448-80c60e99b055" xlink:to="loc_srt_MajorCustomersAxis_bf8d4373-e826-4fb7-8c84-eb99857b07db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_bf8d4373-e826-4fb7-8c84-eb99857b07db_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_bf8d4373-e826-4fb7-8c84-eb99857b07db" xlink:to="loc_srt_NameOfMajorCustomerDomain_bf8d4373-e826-4fb7-8c84-eb99857b07db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_bf8d4373-e826-4fb7-8c84-eb99857b07db" xlink:to="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CollaborationPartnersaBCAndDMember_e6e5701e-7517-4127-a727-19355af895d8" xlink:href="incy-20230930.xsd#incy_CollaborationPartnersaBCAndDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:to="loc_incy_CollaborationPartnersaBCAndDMember_e6e5701e-7517-4127-a727-19355af895d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CustomerAMember_5c3bebc8-fa79-45e4-8840-20211b6d7b21" xlink:href="incy-20230930.xsd#incy_CustomerAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:to="loc_incy_CustomerAMember_5c3bebc8-fa79-45e4-8840-20211b6d7b21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CustomerBMember_5664fc9b-6d17-4791-8c77-8d4b892d95b0" xlink:href="incy-20230930.xsd#incy_CustomerBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:to="loc_incy_CustomerBMember_5664fc9b-6d17-4791-8c77-8d4b892d95b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CustomerCMember_1f5e094c-02e6-4b3a-a6e1-d219e8cfd466" xlink:href="incy-20230930.xsd#incy_CustomerCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:to="loc_incy_CustomerCMember_1f5e094c-02e6-4b3a-a6e1-d219e8cfd466" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CustomerDMember_7093dbc6-b1bc-4f13-bc66-431041f52bfc" xlink:href="incy-20230930.xsd#incy_CustomerDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:to="loc_incy_CustomerDMember_7093dbc6-b1bc-4f13-bc66-431041f52bfc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CustomerEMember_db1aa31b-22cb-48d3-a153-f5d238c9e5b3" xlink:href="incy-20230930.xsd#incy_CustomerEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:to="loc_incy_CustomerEMember_db1aa31b-22cb-48d3-a153-f5d238c9e5b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CustomerABCDAndEMember_eb00986e-5c51-4554-8461-44eaadd224a7" xlink:href="incy-20230930.xsd#incy_CustomerABCDAndEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_da68bb72-7c1e-491f-a95f-1210ee4d20b6" xlink:to="loc_incy_CustomerABCDAndEMember_eb00986e-5c51-4554-8461-44eaadd224a7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3fea0ed4-be18-4f15-aeba-66ada21743b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_4ea2a0e3-96ed-411d-9448-80c60e99b055" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3fea0ed4-be18-4f15-aeba-66ada21743b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_3fea0ed4-be18-4f15-aeba-66ada21743b5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3fea0ed4-be18-4f15-aeba-66ada21743b5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_3fea0ed4-be18-4f15-aeba-66ada21743b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_ac397324-9025-453b-9baa-cdb3d51034ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3fea0ed4-be18-4f15-aeba-66ada21743b5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_ac397324-9025-453b-9baa-cdb3d51034ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueProductLineMember_7e57ff00-e246-436f-a807-81d14c55b7da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SalesRevenueProductLineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_ac397324-9025-453b-9baa-cdb3d51034ea" xlink:to="loc_us-gaap_SalesRevenueProductLineMember_7e57ff00-e246-436f-a807-81d14c55b7da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_6f40ea63-392e-47b0-a223-389420482251" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_ac397324-9025-453b-9baa-cdb3d51034ea" xlink:to="loc_us-gaap_AccountsReceivableMember_6f40ea63-392e-47b0-a223-389420482251" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_f858d634-3889-40dd-ac6c-f67d3f8c3d9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_4ea2a0e3-96ed-411d-9448-80c60e99b055" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_f858d634-3889-40dd-ac6c-f67d3f8c3d9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_f858d634-3889-40dd-ac6c-f67d3f8c3d9b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_f858d634-3889-40dd-ac6c-f67d3f8c3d9b" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_f858d634-3889-40dd-ac6c-f67d3f8c3d9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_af95ab45-bb42-49ff-8f26-d40749bb1bf9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_f858d634-3889-40dd-ac6c-f67d3f8c3d9b" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_af95ab45-bb42-49ff-8f26-d40749bb1bf9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_17e051a8-28c9-4d90-a921-1f950423f8e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_af95ab45-bb42-49ff-8f26-d40749bb1bf9" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_17e051a8-28c9-4d90-a921-1f950423f8e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditConcentrationRiskMember_c9b4c337-6584-4da6-b4e6-bc5f381eeafb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_af95ab45-bb42-49ff-8f26-d40749bb1bf9" xlink:to="loc_us-gaap_CreditConcentrationRiskMember_c9b4c337-6584-4da6-b4e6-bc5f381eeafb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/InventoryDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#InventoryDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/InventoryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryRawMaterialsNetOfReserves_2e8eae13-1f0e-4844-8539-e166143af504" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryRawMaterialsNetOfReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_us-gaap_InventoryRawMaterialsNetOfReserves_2e8eae13-1f0e-4844-8539-e166143af504" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWorkInProcessNetOfReserves_60b542cc-91b4-45f8-82fa-72d5212012a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryWorkInProcessNetOfReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_us-gaap_InventoryWorkInProcessNetOfReserves_60b542cc-91b4-45f8-82fa-72d5212012a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryFinishedGoodsNetOfReserves_427b83e2-849f-4a49-8e95-7e7acc0d0940" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryFinishedGoodsNetOfReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_us-gaap_InventoryFinishedGoodsNetOfReserves_427b83e2-849f-4a49-8e95-7e7acc0d0940" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_InventoryNetCurrentAndNoncurrent_408cc566-84be-4134-bbb1-b96a437ddad4" xlink:href="incy-20230930.xsd#incy_InventoryNetCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_incy_InventoryNetCurrentAndNoncurrent_408cc566-84be-4134-bbb1-b96a437ddad4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_71eabd67-100d-48c4-aaa0-1cacbd82bfeb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_us-gaap_InventoryNet_71eabd67-100d-48c4-aaa0-1cacbd82bfeb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNoncurrent_a1a03b2b-d0f9-409d-b96f-194931222ce1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_us-gaap_InventoryNoncurrent_a1a03b2b-d0f9-409d-b96f-194931222ce1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_InventoryRecordedAsResearchAndDevelopmentExpense_325f62e8-0f0d-466b-b708-e5c49dc7b69c" xlink:href="incy-20230930.xsd#incy_InventoryRecordedAsResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_incy_InventoryRecordedAsResearchAndDevelopmentExpense_325f62e8-0f0d-466b-b708-e5c49dc7b69c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_PeriodOfDeviationFromAverageCostOfGoodsSold_0cc59327-752f-4159-8cac-c43f05e15587" xlink:href="incy-20230930.xsd#incy_PeriodOfDeviationFromAverageCostOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_incy_PeriodOfDeviationFromAverageCostOfGoodsSold_0cc59327-752f-4159-8cac-c43f05e15587" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryCurrentTable_1afd165e-1474-4d09-8f5a-553031f95d89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryCurrentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_50841c0c-5c53-4fc4-8753-46735148a477" xlink:to="loc_us-gaap_InventoryCurrentTable_1afd165e-1474-4d09-8f5a-553031f95d89" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_fed958c5-fb23-42d2-b00e-9870bc0b16c7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_InventoryCurrentTable_1afd165e-1474-4d09-8f5a-553031f95d89" xlink:to="loc_srt_RangeAxis_fed958c5-fb23-42d2-b00e-9870bc0b16c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_fed958c5-fb23-42d2-b00e-9870bc0b16c7_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_fed958c5-fb23-42d2-b00e-9870bc0b16c7" xlink:to="loc_srt_RangeMember_fed958c5-fb23-42d2-b00e-9870bc0b16c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0a8187c3-bbe9-43f2-b72d-7c5e49dd3973" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_fed958c5-fb23-42d2-b00e-9870bc0b16c7" xlink:to="loc_srt_RangeMember_0a8187c3-bbe9-43f2-b72d-7c5e49dd3973" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_1ca0ceb6-7461-4088-a6f7-8c8423c18260" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0a8187c3-bbe9-43f2-b72d-7c5e49dd3973" xlink:to="loc_srt_MinimumMember_1ca0ceb6-7461-4088-a6f7-8c8423c18260" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b0453c94-ec8e-488e-aac6-7a8c03ee482b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0a8187c3-bbe9-43f2-b72d-7c5e49dd3973" xlink:to="loc_srt_MaximumMember_b0453c94-ec8e-488e-aac6-7a8c03ee482b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsNovartisDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsNovartisDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsNovartisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementUpfrontPaymentAndImmediateMilestonePaymentToBeReceived_b13e54ba-62cd-4b4c-a7d6-a857e6291ec2" xlink:href="incy-20230930.xsd#incy_LicenseAgreementUpfrontPaymentAndImmediateMilestonePaymentToBeReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:to="loc_incy_LicenseAgreementUpfrontPaymentAndImmediateMilestonePaymentToBeReceived_b13e54ba-62cd-4b4c-a7d6-a857e6291ec2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementAmountRecognizedAndReceivedForAchievementOfPredefinedMilestone_5fb016d2-d779-40fa-8e19-ca8e6d310c07" xlink:href="incy-20230930.xsd#incy_LicenseAgreementAmountRecognizedAndReceivedForAchievementOfPredefinedMilestone"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:to="loc_incy_LicenseAgreementAmountRecognizedAndReceivedForAchievementOfPredefinedMilestone_5fb016d2-d779-40fa-8e19-ca8e6d310c07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_PercentageOfRoyaltyRatePayments_b24751b2-eac5-442d-ad10-71b67f88d960" xlink:href="incy-20230930.xsd#incy_PercentageOfRoyaltyRatePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:to="loc_incy_PercentageOfRoyaltyRatePayments_b24751b2-eac5-442d-ad10-71b67f88d960" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInRoyaltiesPayable_07bfb002-c0b2-40ba-aa12-f3d36d5633df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInRoyaltiesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:to="loc_us-gaap_IncreaseDecreaseInRoyaltiesPayable_07bfb002-c0b2-40ba-aa12-f3d36d5633df" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_RoyaltiesPayable_76ab1c15-3c33-48c3-bf93-be9b4a163e55" xlink:href="incy-20230930.xsd#incy_RoyaltiesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:to="loc_incy_RoyaltiesPayable_76ab1c15-3c33-48c3-bf93-be9b4a163e55" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_9bf8df29-415e-4507-9f46-45316a6e54b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_9bf8df29-415e-4507-9f46-45316a6e54b9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5012a9c3-8b19-4905-a454-fc5fa68d608d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_a581072f-5c03-4d28-8e7d-a9b2ecee55f1" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5012a9c3-8b19-4905-a454-fc5fa68d608d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneAxis_ab3dc950-1d20-46b4-b086-fa0786f7335a" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5012a9c3-8b19-4905-a454-fc5fa68d608d" xlink:to="loc_incy_AchievementOfMilestoneAxis_ab3dc950-1d20-46b4-b086-fa0786f7335a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_ab3dc950-1d20-46b4-b086-fa0786f7335a_default" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_incy_AchievementOfMilestoneAxis_ab3dc950-1d20-46b4-b086-fa0786f7335a" xlink:to="loc_incy_AchievementOfMilestoneDomain_ab3dc950-1d20-46b4-b086-fa0786f7335a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_b7b331db-3a56-46ef-81d0-7101738bd7c0" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_incy_AchievementOfMilestoneAxis_ab3dc950-1d20-46b4-b086-fa0786f7335a" xlink:to="loc_incy_AchievementOfMilestoneDomain_b7b331db-3a56-46ef-81d0-7101738bd7c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentMilestonesMember_f7e5a9fc-7320-48e2-8e82-f4dde7be796b" xlink:href="incy-20230930.xsd#incy_DevelopmentMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_b7b331db-3a56-46ef-81d0-7101738bd7c0" xlink:to="loc_incy_DevelopmentMilestonesMember_f7e5a9fc-7320-48e2-8e82-f4dde7be796b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_RegulatoryMilestonesMember_37a2b533-eab9-4c69-a8b9-0e082dd22979" xlink:href="incy-20230930.xsd#incy_RegulatoryMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_b7b331db-3a56-46ef-81d0-7101738bd7c0" xlink:to="loc_incy_RegulatoryMilestonesMember_37a2b533-eab9-4c69-a8b9-0e082dd22979" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CommercializationMilestonesMember_20373f78-4e19-495c-88fc-0ab01d89e6a5" xlink:href="incy-20230930.xsd#incy_CommercializationMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_b7b331db-3a56-46ef-81d0-7101738bd7c0" xlink:to="loc_incy_CommercializationMilestonesMember_20373f78-4e19-495c-88fc-0ab01d89e6a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentAndRegulatoryMilestonesMember_44280226-b12c-4044-8599-c71942278f19" xlink:href="incy-20230930.xsd#incy_DevelopmentAndRegulatoryMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_b7b331db-3a56-46ef-81d0-7101738bd7c0" xlink:to="loc_incy_DevelopmentAndRegulatoryMilestonesMember_44280226-b12c-4044-8599-c71942278f19" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ed71efbd-f467-4558-ac4d-650aada53ff3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5012a9c3-8b19-4905-a454-fc5fa68d608d" xlink:to="loc_srt_RangeAxis_ed71efbd-f467-4558-ac4d-650aada53ff3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ed71efbd-f467-4558-ac4d-650aada53ff3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ed71efbd-f467-4558-ac4d-650aada53ff3" xlink:to="loc_srt_RangeMember_ed71efbd-f467-4558-ac4d-650aada53ff3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_74b60546-3b5d-4095-9290-19677ebcb9e2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ed71efbd-f467-4558-ac4d-650aada53ff3" xlink:to="loc_srt_RangeMember_74b60546-3b5d-4095-9290-19677ebcb9e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_62129dc4-6c1d-4784-9d80-09b4b014aaed" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_74b60546-3b5d-4095-9290-19677ebcb9e2" xlink:to="loc_srt_MinimumMember_62129dc4-6c1d-4784-9d80-09b4b014aaed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_33d6d270-cfc4-4485-a0a0-1badcdbc6137" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_74b60546-3b5d-4095-9290-19677ebcb9e2" xlink:to="loc_srt_MaximumMember_33d6d270-cfc4-4485-a0a0-1badcdbc6137" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_c7220ec4-4cfb-4b6e-bdd0-df460a5cd3a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5012a9c3-8b19-4905-a454-fc5fa68d608d" xlink:to="loc_us-gaap_TypeOfArrangementAxis_c7220ec4-4cfb-4b6e-bdd0-df460a5cd3a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_c7220ec4-4cfb-4b6e-bdd0-df460a5cd3a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_c7220ec4-4cfb-4b6e-bdd0-df460a5cd3a3" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_c7220ec4-4cfb-4b6e-bdd0-df460a5cd3a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_6eba93d8-dea5-4afb-a661-ee8e14c63cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_c7220ec4-4cfb-4b6e-bdd0-df460a5cd3a3" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_6eba93d8-dea5-4afb-a661-ee8e14c63cfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_NovartisMember_1ee94ef9-522c-4b04-af83-243dfbc29e0b" xlink:href="incy-20230930.xsd#incy_NovartisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_6eba93d8-dea5-4afb-a661-ee8e14c63cfe" xlink:to="loc_incy_NovartisMember_1ee94ef9-522c-4b04-af83-243dfbc29e0b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_b64c81ac-4a5f-4f86-ba71-232b06d5376a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5012a9c3-8b19-4905-a454-fc5fa68d608d" xlink:to="loc_srt_ProductOrServiceAxis_b64c81ac-4a5f-4f86-ba71-232b06d5376a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b64c81ac-4a5f-4f86-ba71-232b06d5376a_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_b64c81ac-4a5f-4f86-ba71-232b06d5376a" xlink:to="loc_srt_ProductsAndServicesDomain_b64c81ac-4a5f-4f86-ba71-232b06d5376a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_1b2c54a1-36cf-4773-92ef-d6b9505cd03d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_b64c81ac-4a5f-4f86-ba71-232b06d5376a" xlink:to="loc_srt_ProductsAndServicesDomain_1b2c54a1-36cf-4773-92ef-d6b9505cd03d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RoyaltyMember_16e6573c-5a51-4662-8f74-2d460624828b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RoyaltyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_1b2c54a1-36cf-4773-92ef-d6b9505cd03d" xlink:to="loc_us-gaap_RoyaltyMember_16e6573c-5a51-4662-8f74-2d460624828b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_JakaviMember_9d35e816-1863-461f-8242-17772d0fa1ad" xlink:href="incy-20230930.xsd#incy_JakaviMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RoyaltyMember_16e6573c-5a51-4662-8f74-2d460624828b" xlink:to="loc_incy_JakaviMember_9d35e816-1863-461f-8242-17772d0fa1ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_JAKAFIMember_200f5807-5153-4b21-a214-37f2c675002b" xlink:href="incy-20230930.xsd#incy_JAKAFIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RoyaltyMember_16e6573c-5a51-4662-8f74-2d460624828b" xlink:to="loc_incy_JAKAFIMember_200f5807-5153-4b21-a214-37f2c675002b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MilestoneAndContractRevenueMember_b6888fbc-b8d9-49c0-a365-3374d79c30e1" xlink:href="incy-20230930.xsd#incy_MilestoneAndContractRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_1b2c54a1-36cf-4773-92ef-d6b9505cd03d" xlink:to="loc_incy_MilestoneAndContractRevenueMember_b6888fbc-b8d9-49c0-a365-3374d79c30e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_TABRECTAPRODUCTANDSERVICESMember_81f25eab-dc24-4d38-8252-54fd960d1d47" xlink:href="incy-20230930.xsd#incy_TABRECTAPRODUCTANDSERVICESMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_1b2c54a1-36cf-4773-92ef-d6b9505cd03d" xlink:to="loc_incy_TABRECTAPRODUCTANDSERVICESMember_81f25eab-dc24-4d38-8252-54fd960d1d47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_99463679-3bf7-49a9-8f4d-3fa3c3f78d33" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5012a9c3-8b19-4905-a454-fc5fa68d608d" xlink:to="loc_srt_StatementGeographicalAxis_99463679-3bf7-49a9-8f4d-3fa3c3f78d33" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_99463679-3bf7-49a9-8f4d-3fa3c3f78d33_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_99463679-3bf7-49a9-8f4d-3fa3c3f78d33" xlink:to="loc_srt_SegmentGeographicalDomain_99463679-3bf7-49a9-8f4d-3fa3c3f78d33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_de9f4a5f-34cd-4628-8d51-f528996bcac8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_99463679-3bf7-49a9-8f4d-3fa3c3f78d33" xlink:to="loc_srt_SegmentGeographicalDomain_de9f4a5f-34cd-4628-8d51-f528996bcac8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_d3d96aab-33bc-42f2-b0a0-b2e963a82522" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_de9f4a5f-34cd-4628-8d51-f528996bcac8" xlink:to="loc_country_US_d3d96aab-33bc-42f2-b0a0-b2e963a82522" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_7dd86f78-1d1b-4049-99ea-fff987000992" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_de9f4a5f-34cd-4628-8d51-f528996bcac8" xlink:to="loc_us-gaap_NonUsMember_7dd86f78-1d1b-4049-99ea-fff987000992" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsLillyDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsLillyDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsLillyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementUpfrontPaymentAndImmediateMilestonePaymentToBeReceived_cf9e1c15-9aa9-421f-9354-df7633c890ce" xlink:href="incy-20230930.xsd#incy_LicenseAgreementUpfrontPaymentAndImmediateMilestonePaymentToBeReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:to="loc_incy_LicenseAgreementUpfrontPaymentAndImmediateMilestonePaymentToBeReceived_cf9e1c15-9aa9-421f-9354-df7633c890ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementAmountRecognizedAndReceivedForAchievementOfPredefinedMilestone_990c8a34-b655-40c2-81c5-b76a28a0f411" xlink:href="incy-20230930.xsd#incy_LicenseAgreementAmountRecognizedAndReceivedForAchievementOfPredefinedMilestone"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:to="loc_incy_LicenseAgreementAmountRecognizedAndReceivedForAchievementOfPredefinedMilestone_990c8a34-b655-40c2-81c5-b76a28a0f411" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_55fb8125-f433-4a0e-b298-d4feebb27eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_55fb8125-f433-4a0e-b298-d4feebb27eb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInRoyaltiesPayable_59ddb05d-09a6-4712-8b40-e554dc2cbc52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInRoyaltiesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:to="loc_us-gaap_IncreaseDecreaseInRoyaltiesPayable_59ddb05d-09a6-4712-8b40-e554dc2cbc52" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementAdditionalMilestonePayments_3f187555-811f-4f43-8bc5-644b06732a7c" xlink:href="incy-20230930.xsd#incy_LicenseAgreementAdditionalMilestonePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:to="loc_incy_LicenseAgreementAdditionalMilestonePayments_3f187555-811f-4f43-8bc5-644b06732a7c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_65b37ff6-e432-4756-b349-18d93a0c044a" xlink:href="incy-20230930.xsd#incy_LicenseAgreementMilestonePaymentAmountPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:to="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_65b37ff6-e432-4756-b349-18d93a0c044a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_3e049d67-5ed2-4d2e-9a9c-94fa6176003b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_f2bdf8c9-cfbb-4940-b7d7-d81520c12638" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_3e049d67-5ed2-4d2e-9a9c-94fa6176003b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneAxis_f897a054-72c6-4dba-8303-7d25e581fd08" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_3e049d67-5ed2-4d2e-9a9c-94fa6176003b" xlink:to="loc_incy_AchievementOfMilestoneAxis_f897a054-72c6-4dba-8303-7d25e581fd08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_f897a054-72c6-4dba-8303-7d25e581fd08_default" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_incy_AchievementOfMilestoneAxis_f897a054-72c6-4dba-8303-7d25e581fd08" xlink:to="loc_incy_AchievementOfMilestoneDomain_f897a054-72c6-4dba-8303-7d25e581fd08_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_e2125091-e167-4f3c-8793-9738011368d1" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_incy_AchievementOfMilestoneAxis_f897a054-72c6-4dba-8303-7d25e581fd08" xlink:to="loc_incy_AchievementOfMilestoneDomain_e2125091-e167-4f3c-8793-9738011368d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentMilestonesMember_9eea977d-bd0c-4eb1-afde-72ce804afaab" xlink:href="incy-20230930.xsd#incy_DevelopmentMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_e2125091-e167-4f3c-8793-9738011368d1" xlink:to="loc_incy_DevelopmentMilestonesMember_9eea977d-bd0c-4eb1-afde-72ce804afaab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_RegulatoryMilestonesMember_6676d0d7-f4f2-43a5-8efa-13a5f616d2c5" xlink:href="incy-20230930.xsd#incy_RegulatoryMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_e2125091-e167-4f3c-8793-9738011368d1" xlink:to="loc_incy_RegulatoryMilestonesMember_6676d0d7-f4f2-43a5-8efa-13a5f616d2c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CommercializationMilestonesMember_a359cda4-3ff6-460f-9de6-29a3ec4e4b35" xlink:href="incy-20230930.xsd#incy_CommercializationMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_e2125091-e167-4f3c-8793-9738011368d1" xlink:to="loc_incy_CommercializationMilestonesMember_a359cda4-3ff6-460f-9de6-29a3ec4e4b35" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_81b41a29-fb1d-4a3a-88e5-2bb387923dc5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_3e049d67-5ed2-4d2e-9a9c-94fa6176003b" xlink:to="loc_srt_RangeAxis_81b41a29-fb1d-4a3a-88e5-2bb387923dc5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_81b41a29-fb1d-4a3a-88e5-2bb387923dc5_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_81b41a29-fb1d-4a3a-88e5-2bb387923dc5" xlink:to="loc_srt_RangeMember_81b41a29-fb1d-4a3a-88e5-2bb387923dc5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e8455ea6-c755-4790-bd07-612a4f7eeb68" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_81b41a29-fb1d-4a3a-88e5-2bb387923dc5" xlink:to="loc_srt_RangeMember_e8455ea6-c755-4790-bd07-612a4f7eeb68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c65fdba0-aab6-4214-b782-bf4d229da4cf" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e8455ea6-c755-4790-bd07-612a4f7eeb68" xlink:to="loc_srt_MaximumMember_c65fdba0-aab6-4214-b782-bf4d229da4cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_aa6e54f4-5be2-4e8a-9a51-789a390ac041" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_3e049d67-5ed2-4d2e-9a9c-94fa6176003b" xlink:to="loc_us-gaap_TypeOfArrangementAxis_aa6e54f4-5be2-4e8a-9a51-789a390ac041" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_aa6e54f4-5be2-4e8a-9a51-789a390ac041_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_aa6e54f4-5be2-4e8a-9a51-789a390ac041" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_aa6e54f4-5be2-4e8a-9a51-789a390ac041_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_0d707f7e-8f9e-4343-a932-4be43e8470a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_aa6e54f4-5be2-4e8a-9a51-789a390ac041" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_0d707f7e-8f9e-4343-a932-4be43e8470a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_EliLillyMember_b07f7352-5141-4dd1-90e0-fedb196de581" xlink:href="incy-20230930.xsd#incy_EliLillyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_0d707f7e-8f9e-4343-a932-4be43e8470a3" xlink:to="loc_incy_EliLillyMember_b07f7352-5141-4dd1-90e0-fedb196de581" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_a54011a6-89f4-447f-825c-f86d036915e7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_3e049d67-5ed2-4d2e-9a9c-94fa6176003b" xlink:to="loc_srt_ProductOrServiceAxis_a54011a6-89f4-447f-825c-f86d036915e7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a54011a6-89f4-447f-825c-f86d036915e7_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_a54011a6-89f4-447f-825c-f86d036915e7" xlink:to="loc_srt_ProductsAndServicesDomain_a54011a6-89f4-447f-825c-f86d036915e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_dde80709-f259-4066-98c6-d946f6cb387d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_a54011a6-89f4-447f-825c-f86d036915e7" xlink:to="loc_srt_ProductsAndServicesDomain_dde80709-f259-4066-98c6-d946f6cb387d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_OlumiantMember_1a5d7009-a1f1-40b5-bcc7-7ee4c55cf320" xlink:href="incy-20230930.xsd#incy_OlumiantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_dde80709-f259-4066-98c6-d946f6cb387d" xlink:to="loc_incy_OlumiantMember_1a5d7009-a1f1-40b5-bcc7-7ee4c55cf320" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_OlumiantRoyaltyMember_f596a1d2-6e0f-46df-870d-a38d763f52a3" xlink:href="incy-20230930.xsd#incy_OlumiantRoyaltyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_dde80709-f259-4066-98c6-d946f6cb387d" xlink:to="loc_incy_OlumiantRoyaltyMember_f596a1d2-6e0f-46df-870d-a38d763f52a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_GvhdMember_84ec0a56-73ee-4724-aa93-ac00ce962ba4" xlink:href="incy-20230930.xsd#incy_GvhdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_dde80709-f259-4066-98c6-d946f6cb387d" xlink:to="loc_incy_GvhdMember_84ec0a56-73ee-4724-aa93-ac00ce962ba4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_GVHDMember_e94308b3-f73d-4a59-86cf-2c99a68b9e54" xlink:href="incy-20230930.xsd#incy_GVHDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_dde80709-f259-4066-98c6-d946f6cb387d" xlink:to="loc_incy_GVHDMember_e94308b3-f73d-4a59-86cf-2c99a68b9e54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_a6a69d65-fb65-4716-8c3f-1cf4d9be3738" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_3e049d67-5ed2-4d2e-9a9c-94fa6176003b" xlink:to="loc_srt_StatementGeographicalAxis_a6a69d65-fb65-4716-8c3f-1cf4d9be3738" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_a6a69d65-fb65-4716-8c3f-1cf4d9be3738_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_a6a69d65-fb65-4716-8c3f-1cf4d9be3738" xlink:to="loc_srt_SegmentGeographicalDomain_a6a69d65-fb65-4716-8c3f-1cf4d9be3738_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_b805f4e4-8dfb-42a3-b719-c0f538ed1aea" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_a6a69d65-fb65-4716-8c3f-1cf4d9be3738" xlink:to="loc_srt_SegmentGeographicalDomain_b805f4e4-8dfb-42a3-b719-c0f538ed1aea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_dba632dc-98ff-4513-aac6-2e726c57fef6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b805f4e4-8dfb-42a3-b719-c0f538ed1aea" xlink:to="loc_us-gaap_NonUsMember_dba632dc-98ff-4513-aac6-2e726c57fef6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EuropeMember_1c11f0bf-0d24-441b-9bf9-83fa6d9efe7f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b805f4e4-8dfb-42a3-b719-c0f538ed1aea" xlink:to="loc_srt_EuropeMember_1c11f0bf-0d24-441b-9bf9-83fa6d9efe7f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsAgenusDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsAgenusDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsAgenusDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_d21c5c17-7216-4458-9ede-65a77db958c3" xlink:href="incy-20230930.xsd#incy_LicenseAgreementMilestonePaymentAmountPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:to="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_d21c5c17-7216-4458-9ede-65a77db958c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementAdditionalMilestonePayments_0eca4615-138c-4f01-b818-6bec575f17e7" xlink:href="incy-20230930.xsd#incy_LicenseAgreementAdditionalMilestonePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:to="loc_incy_LicenseAgreementAdditionalMilestonePayments_0eca4615-138c-4f01-b818-6bec575f17e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_81ccd3c2-969b-4573-a5d6-3fa831f049b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_81ccd3c2-969b-4573-a5d6-3fa831f049b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermInvestments_b0db4de8-254c-4c80-99a2-89348bc464bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:to="loc_us-gaap_LongTermInvestments_b0db4de8-254c-4c80-99a2-89348bc464bd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_5791da69-93b4-4d24-8bf6-c8da30bed655" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_5791da69-93b4-4d24-8bf6-c8da30bed655" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_InvestmentOwnedBalanceSharesAcquired_4ca9befa-be2d-4d9d-befb-6ed8bdad7c2b" xlink:href="incy-20230930.xsd#incy_InvestmentOwnedBalanceSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:to="loc_incy_InvestmentOwnedBalanceSharesAcquired_4ca9befa-be2d-4d9d-befb-6ed8bdad7c2b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1695d461-8dd9-440f-8010-29de782b17e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_050584fa-0aa4-4c82-a3e2-3732259cca43" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1695d461-8dd9-440f-8010-29de782b17e0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneAxis_86f4de0a-2934-4e82-9ceb-e6aba355e745" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1695d461-8dd9-440f-8010-29de782b17e0" xlink:to="loc_incy_AchievementOfMilestoneAxis_86f4de0a-2934-4e82-9ceb-e6aba355e745" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_86f4de0a-2934-4e82-9ceb-e6aba355e745_default" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_incy_AchievementOfMilestoneAxis_86f4de0a-2934-4e82-9ceb-e6aba355e745" xlink:to="loc_incy_AchievementOfMilestoneDomain_86f4de0a-2934-4e82-9ceb-e6aba355e745_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_083f6011-a2ac-4d2e-87ca-0af33d7e6311" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_incy_AchievementOfMilestoneAxis_86f4de0a-2934-4e82-9ceb-e6aba355e745" xlink:to="loc_incy_AchievementOfMilestoneDomain_083f6011-a2ac-4d2e-87ca-0af33d7e6311" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentRegulatoryAndCommercializationMilestonesMember_a7f70132-9596-4d8b-9778-24472d687146" xlink:href="incy-20230930.xsd#incy_DevelopmentRegulatoryAndCommercializationMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_083f6011-a2ac-4d2e-87ca-0af33d7e6311" xlink:to="loc_incy_DevelopmentRegulatoryAndCommercializationMilestonesMember_a7f70132-9596-4d8b-9778-24472d687146" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_20929786-09be-4b0d-ad63-18f658f1640a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1695d461-8dd9-440f-8010-29de782b17e0" xlink:to="loc_us-gaap_TypeOfArrangementAxis_20929786-09be-4b0d-ad63-18f658f1640a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_20929786-09be-4b0d-ad63-18f658f1640a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_20929786-09be-4b0d-ad63-18f658f1640a" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_20929786-09be-4b0d-ad63-18f658f1640a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_bb83235e-a93f-4e35-b956-baf5fb84cc84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_20929786-09be-4b0d-ad63-18f658f1640a" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_bb83235e-a93f-4e35-b956-baf5fb84cc84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AgenusMember_bb991f9a-2103-4010-a52c-042f662bc0e6" xlink:href="incy-20230930.xsd#incy_AgenusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_bb83235e-a93f-4e35-b956-baf5fb84cc84" xlink:to="loc_incy_AgenusMember_bb991f9a-2103-4010-a52c-042f662bc0e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a4c3727-a749-4e8e-8eac-ebd78f93f58e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1695d461-8dd9-440f-8010-29de782b17e0" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a4c3727-a749-4e8e-8eac-ebd78f93f58e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_8a4c3727-a749-4e8e-8eac-ebd78f93f58e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a4c3727-a749-4e8e-8eac-ebd78f93f58e" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_8a4c3727-a749-4e8e-8eac-ebd78f93f58e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_3712545e-e30f-4deb-bc58-f18c62060a89" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a4c3727-a749-4e8e-8eac-ebd78f93f58e" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_3712545e-e30f-4deb-bc58-f18c62060a89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AgenusMember_5204c799-2bfd-477d-85f5-1a08c8733948" xlink:href="incy-20230930.xsd#incy_AgenusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_3712545e-e30f-4deb-bc58-f18c62060a89" xlink:to="loc_incy_AgenusMember_5204c799-2bfd-477d-85f5-1a08c8733948" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MiNKMember_2ad38783-79b2-4508-b089-63e4a02defd9" xlink:href="incy-20230930.xsd#incy_MiNKMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_3712545e-e30f-4deb-bc58-f18c62060a89" xlink:to="loc_incy_MiNKMember_2ad38783-79b2-4508-b089-63e4a02defd9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsMerusDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsMerusDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsMerusDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementMaximumNumberOfIndependentPrograms_dca6373f-bbfe-4831-9590-d3884fb8bdfe" xlink:href="incy-20230930.xsd#incy_LicenseAgreementMaximumNumberOfIndependentPrograms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_incy_LicenseAgreementMaximumNumberOfIndependentPrograms_dca6373f-bbfe-4831-9590-d3884fb8bdfe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_433ae9ab-079c-40ae-a190-e7131d9cae2c" xlink:href="incy-20230930.xsd#incy_LicenseAgreementMilestonePaymentAmountPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_433ae9ab-079c-40ae-a190-e7131d9cae2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_PurchaseOfCommonStockUnderStockPurchaseAgreement_57bc066d-c4ae-4fc7-aa07-b23ebaaab31a" xlink:href="incy-20230930.xsd#incy_PurchaseOfCommonStockUnderStockPurchaseAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_incy_PurchaseOfCommonStockUnderStockPurchaseAgreement_57bc066d-c4ae-4fc7-aa07-b23ebaaab31a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentAggregateCost_a1dc6fe5-b2a4-4a1d-b8a4-717f167eb8cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentAggregateCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_us-gaap_EquityMethodInvestmentAggregateCost_a1dc6fe5-b2a4-4a1d-b8a4-717f167eb8cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_e21e3496-7daa-406a-9cf7-d699b6ea88c8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_e21e3496-7daa-406a-9cf7-d699b6ea88c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_d32286bc-a3a4-4ad3-9fe7-15580c74d51d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_d32286bc-a3a4-4ad3-9fe7-15580c74d51d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_13a2dbfc-7895-45e0-b19b-0f150572c343" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_13a2dbfc-7895-45e0-b19b-0f150572c343" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_4e541465-fa2e-4b54-a3ab-5458b74d109c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_9be56f29-67c8-464c-b1f5-89def4eb6124" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_4e541465-fa2e-4b54-a3ab-5458b74d109c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_0a166c3c-c223-49a2-9154-24ce215af53e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_4e541465-fa2e-4b54-a3ab-5458b74d109c" xlink:to="loc_us-gaap_TypeOfArrangementAxis_0a166c3c-c223-49a2-9154-24ce215af53e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_0a166c3c-c223-49a2-9154-24ce215af53e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_0a166c3c-c223-49a2-9154-24ce215af53e" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_0a166c3c-c223-49a2-9154-24ce215af53e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_e1a2c56d-b264-4105-a704-db65210aea6c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_0a166c3c-c223-49a2-9154-24ce215af53e" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_e1a2c56d-b264-4105-a704-db65210aea6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MerusNVMember_fd65fce4-d171-4b76-8fb6-d1bb68efb1f5" xlink:href="incy-20230930.xsd#incy_MerusNVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_e1a2c56d-b264-4105-a704-db65210aea6c" xlink:to="loc_incy_MerusNVMember_fd65fce4-d171-4b76-8fb6-d1bb68efb1f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d1d2d32a-6acc-4693-a5a5-936c17b7a998" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_4e541465-fa2e-4b54-a3ab-5458b74d109c" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d1d2d32a-6acc-4693-a5a5-936c17b7a998" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_d1d2d32a-6acc-4693-a5a5-936c17b7a998_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d1d2d32a-6acc-4693-a5a5-936c17b7a998" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_d1d2d32a-6acc-4693-a5a5-936c17b7a998_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_08293f4e-1411-4582-86e8-9a63f158f0ca" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_d1d2d32a-6acc-4693-a5a5-936c17b7a998" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_08293f4e-1411-4582-86e8-9a63f158f0ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MerusNVMember_71ce18e2-cd6a-4af1-b734-c9abc4b83d2f" xlink:href="incy-20230930.xsd#incy_MerusNVMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_08293f4e-1411-4582-86e8-9a63f158f0ca" xlink:to="loc_incy_MerusNVMember_71ce18e2-cd6a-4af1-b734-c9abc4b83d2f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsMacroGenicsDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsMacroGenicsDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsMacroGenicsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_54855251-a4db-4ab0-a04e-145a81eec2e5" xlink:href="incy-20230930.xsd#incy_LicenseAgreementMilestonePaymentAmountPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:to="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_54855251-a4db-4ab0-a04e-145a81eec2e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementMilestonePaymentUsefulLife_929c06dd-d459-42e3-936b-7d3d751e01c5" xlink:href="incy-20230930.xsd#incy_LicenseAgreementMilestonePaymentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:to="loc_incy_LicenseAgreementMilestonePaymentUsefulLife_929c06dd-d459-42e3-936b-7d3d751e01c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementAdditionalMilestonePayments_1995ef89-387e-4203-93bb-f3d4a0b14f91" xlink:href="incy-20230930.xsd#incy_LicenseAgreementAdditionalMilestonePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:to="loc_incy_LicenseAgreementAdditionalMilestonePayments_1995ef89-387e-4203-93bb-f3d4a0b14f91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_PercentageOfRoyaltyRatePayments_02b99cf4-712d-486a-a37e-95784c568dec" xlink:href="incy-20230930.xsd#incy_PercentageOfRoyaltyRatePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:to="loc_incy_PercentageOfRoyaltyRatePayments_02b99cf4-712d-486a-a37e-95784c568dec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_4861ccf9-57c4-4f93-a84f-6bfdd2b0d4cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_4861ccf9-57c4-4f93-a84f-6bfdd2b0d4cd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_396f9e3c-3239-49d5-9dd3-0ff068185d17" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:to="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_396f9e3c-3239-49d5-9dd3-0ff068185d17" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1fb42395-9e58-42c3-9f07-26741ec60dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_865f0551-92e2-4a31-a11a-7c88b4562cb1" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1fb42395-9e58-42c3-9f07-26741ec60dcb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneAxis_b7863be6-8701-4b60-be9f-be69f7c24147" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1fb42395-9e58-42c3-9f07-26741ec60dcb" xlink:to="loc_incy_AchievementOfMilestoneAxis_b7863be6-8701-4b60-be9f-be69f7c24147" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_b7863be6-8701-4b60-be9f-be69f7c24147_default" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_incy_AchievementOfMilestoneAxis_b7863be6-8701-4b60-be9f-be69f7c24147" xlink:to="loc_incy_AchievementOfMilestoneDomain_b7863be6-8701-4b60-be9f-be69f7c24147_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_80ca6f44-b0a0-4504-9dd9-eb46cbed6163" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_incy_AchievementOfMilestoneAxis_b7863be6-8701-4b60-be9f-be69f7c24147" xlink:to="loc_incy_AchievementOfMilestoneDomain_80ca6f44-b0a0-4504-9dd9-eb46cbed6163" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_RegulatoryMilestoneMember_becc3226-b755-4069-83dc-c76f47bde0e8" xlink:href="incy-20230930.xsd#incy_RegulatoryMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_80ca6f44-b0a0-4504-9dd9-eb46cbed6163" xlink:to="loc_incy_RegulatoryMilestoneMember_becc3226-b755-4069-83dc-c76f47bde0e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentAndRegulatoryMilestonesMember_ea67332c-96f1-4c21-8613-fe9217f51ba9" xlink:href="incy-20230930.xsd#incy_DevelopmentAndRegulatoryMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_80ca6f44-b0a0-4504-9dd9-eb46cbed6163" xlink:to="loc_incy_DevelopmentAndRegulatoryMilestonesMember_ea67332c-96f1-4c21-8613-fe9217f51ba9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentMilestonesMember_b23d6506-0485-4c77-b2e2-d72faf04f761" xlink:href="incy-20230930.xsd#incy_DevelopmentMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_DevelopmentAndRegulatoryMilestonesMember_ea67332c-96f1-4c21-8613-fe9217f51ba9" xlink:to="loc_incy_DevelopmentMilestonesMember_b23d6506-0485-4c77-b2e2-d72faf04f761" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentalAndRegulatoryMilestonesMember_415b5105-155e-4cea-a7bd-b9772fe4f477" xlink:href="incy-20230930.xsd#incy_DevelopmentalAndRegulatoryMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_80ca6f44-b0a0-4504-9dd9-eb46cbed6163" xlink:to="loc_incy_DevelopmentalAndRegulatoryMilestonesMember_415b5105-155e-4cea-a7bd-b9772fe4f477" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CommercializationMilestonesMember_9b7b3db3-0437-4aee-a526-81d899a3a59f" xlink:href="incy-20230930.xsd#incy_CommercializationMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_80ca6f44-b0a0-4504-9dd9-eb46cbed6163" xlink:to="loc_incy_CommercializationMilestonesMember_9b7b3db3-0437-4aee-a526-81d899a3a59f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_08d17ddb-3df9-4cdd-b4db-f35fb6456834" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1fb42395-9e58-42c3-9f07-26741ec60dcb" xlink:to="loc_us-gaap_TypeOfArrangementAxis_08d17ddb-3df9-4cdd-b4db-f35fb6456834" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_08d17ddb-3df9-4cdd-b4db-f35fb6456834_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_08d17ddb-3df9-4cdd-b4db-f35fb6456834" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_08d17ddb-3df9-4cdd-b4db-f35fb6456834_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_47c1edd0-3e04-490d-bd0f-3fd4407ee84a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_08d17ddb-3df9-4cdd-b4db-f35fb6456834" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_47c1edd0-3e04-490d-bd0f-3fd4407ee84a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MacrogenicsMember_1fa722de-1360-4cc1-8119-a13f25baabe3" xlink:href="incy-20230930.xsd#incy_MacrogenicsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_47c1edd0-3e04-490d-bd0f-3fd4407ee84a" xlink:to="loc_incy_MacrogenicsMember_1fa722de-1360-4cc1-8119-a13f25baabe3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7a663a32-93f2-4da1-8b52-ffe4c4da7de2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1fb42395-9e58-42c3-9f07-26741ec60dcb" xlink:to="loc_srt_RangeAxis_7a663a32-93f2-4da1-8b52-ffe4c4da7de2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7a663a32-93f2-4da1-8b52-ffe4c4da7de2_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7a663a32-93f2-4da1-8b52-ffe4c4da7de2" xlink:to="loc_srt_RangeMember_7a663a32-93f2-4da1-8b52-ffe4c4da7de2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_439e49f4-8d28-4f27-8981-3c3eec819d18" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7a663a32-93f2-4da1-8b52-ffe4c4da7de2" xlink:to="loc_srt_RangeMember_439e49f4-8d28-4f27-8981-3c3eec819d18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_e65ccda1-2036-4093-b016-1925f80f888a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_439e49f4-8d28-4f27-8981-3c3eec819d18" xlink:to="loc_srt_MinimumMember_e65ccda1-2036-4093-b016-1925f80f888a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d6e99354-7bfa-4969-8172-b3d22537cab4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_439e49f4-8d28-4f27-8981-3c3eec819d18" xlink:to="loc_srt_MaximumMember_d6e99354-7bfa-4969-8172-b3d22537cab4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_d84f9453-5d04-485c-bfa4-b1ff60f58496" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1fb42395-9e58-42c3-9f07-26741ec60dcb" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_d84f9453-5d04-485c-bfa4-b1ff60f58496" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_d84f9453-5d04-485c-bfa4-b1ff60f58496_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_d84f9453-5d04-485c-bfa4-b1ff60f58496" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_d84f9453-5d04-485c-bfa4-b1ff60f58496_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_ba498400-84b4-43cf-92fc-f5b5354abf0e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_d84f9453-5d04-485c-bfa4-b1ff60f58496" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_ba498400-84b4-43cf-92fc-f5b5354abf0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_979559da-fdb0-41c7-b874-fcfe114886de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_ba498400-84b4-43cf-92fc-f5b5354abf0e" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_979559da-fdb0-41c7-b874-fcfe114886de" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsSyrosDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsSyrosDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsSyrosDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_bdf631d9-e57f-476e-8fc3-b26a8e098a6f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_NumberOfProgramTargets_ae1c6535-c52a-436b-a2af-a26d81bd97e2" xlink:href="incy-20230930.xsd#incy_NumberOfProgramTargets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bdf631d9-e57f-476e-8fc3-b26a8e098a6f" xlink:to="loc_incy_NumberOfProgramTargets_ae1c6535-c52a-436b-a2af-a26d81bd97e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_66da25f2-4aaf-485f-ad4d-9c69c85517cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bdf631d9-e57f-476e-8fc3-b26a8e098a6f" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_66da25f2-4aaf-485f-ad4d-9c69c85517cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermInvestments_bda4c62b-9613-433e-90c7-d35ef5447cf2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bdf631d9-e57f-476e-8fc3-b26a8e098a6f" xlink:to="loc_us-gaap_LongTermInvestments_bda4c62b-9613-433e-90c7-d35ef5447cf2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_ad69ba73-81b1-4a74-a2e2-8360fb1428fa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bdf631d9-e57f-476e-8fc3-b26a8e098a6f" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_ad69ba73-81b1-4a74-a2e2-8360fb1428fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6364491a-1456-40c1-a6f3-b2614c6f87dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bdf631d9-e57f-476e-8fc3-b26a8e098a6f" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6364491a-1456-40c1-a6f3-b2614c6f87dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_b9035dd5-cb0f-4b74-aa6b-a0dade5cc18c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6364491a-1456-40c1-a6f3-b2614c6f87dd" xlink:to="loc_us-gaap_TypeOfArrangementAxis_b9035dd5-cb0f-4b74-aa6b-a0dade5cc18c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_b9035dd5-cb0f-4b74-aa6b-a0dade5cc18c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_b9035dd5-cb0f-4b74-aa6b-a0dade5cc18c" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_b9035dd5-cb0f-4b74-aa6b-a0dade5cc18c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d1e51cc6-d747-451f-a417-095aaf4f0040" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_b9035dd5-cb0f-4b74-aa6b-a0dade5cc18c" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d1e51cc6-d747-451f-a417-095aaf4f0040" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_SyrosPharmaceuticalsIncMember_b4af9686-0a59-4c51-80e1-874b26102448" xlink:href="incy-20230930.xsd#incy_SyrosPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d1e51cc6-d747-451f-a417-095aaf4f0040" xlink:to="loc_incy_SyrosPharmaceuticalsIncMember_b4af9686-0a59-4c51-80e1-874b26102448" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_905d2076-ac29-413a-964b-5baba4342d12" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6364491a-1456-40c1-a6f3-b2614c6f87dd" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_905d2076-ac29-413a-964b-5baba4342d12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_905d2076-ac29-413a-964b-5baba4342d12_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_905d2076-ac29-413a-964b-5baba4342d12" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_905d2076-ac29-413a-964b-5baba4342d12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_3cc1424a-f7eb-4b2e-a934-42cbdbedea1e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_905d2076-ac29-413a-964b-5baba4342d12" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_3cc1424a-f7eb-4b2e-a934-42cbdbedea1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_SyrosPharmaceuticalsIncMember_534f4c03-a852-4807-86e1-0c109d853d65" xlink:href="incy-20230930.xsd#incy_SyrosPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_3cc1424a-f7eb-4b2e-a934-42cbdbedea1e" xlink:to="loc_incy_SyrosPharmaceuticalsIncMember_534f4c03-a852-4807-86e1-0c109d853d65" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsMorphoSysDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsMorphoSysDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsMorphoSysDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementPercentageOfFutureGlobalDevelopmentCostsFunded_4cf4eaa7-2333-4d96-9013-ab70c1e354c9" xlink:href="incy-20230930.xsd#incy_LicenseAgreementPercentageOfFutureGlobalDevelopmentCostsFunded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_incy_LicenseAgreementPercentageOfFutureGlobalDevelopmentCostsFunded_4cf4eaa7-2333-4d96-9013-ab70c1e354c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementAdditionalMilestonePayments_db9c4b76-b827-44e9-970d-b29054a456a3" xlink:href="incy-20230930.xsd#incy_LicenseAgreementAdditionalMilestonePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_incy_LicenseAgreementAdditionalMilestonePayments_db9c4b76-b827-44e9-970d-b29054a456a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_fda538bb-5463-49b9-b39c-9759b9bb8ea2" xlink:href="incy-20230930.xsd#incy_LicenseAgreementMilestonePaymentAmountPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_incy_LicenseAgreementMilestonePaymentAmountPaid_fda538bb-5463-49b9-b39c-9759b9bb8ea2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_cfb69adc-4e07-417f-b306-97cd518b202f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_cfb69adc-4e07-417f-b306-97cd518b202f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_SubsidiaryStockConversionRatio_d1bd402f-35c7-48c7-812d-438e6b6d74f2" xlink:href="incy-20230930.xsd#incy_SubsidiaryStockConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_incy_SubsidiaryStockConversionRatio_d1bd402f-35c7-48c7-812d-438e6b6d74f2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_f8c9a29e-3d89-4d4f-bbaf-42976b5ec576" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_f8c9a29e-3d89-4d4f-bbaf-42976b5ec576" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_dbe4f185-b423-421c-8250-27cfee88cf06" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_dbe4f185-b423-421c-8250-27cfee88cf06" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CollaborationAgreementProfitLossSharingRatio_ef0f6dac-a3ad-402c-8292-442f6561aaa2" xlink:href="incy-20230930.xsd#incy_CollaborationAgreementProfitLossSharingRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_incy_CollaborationAgreementProfitLossSharingRatio_ef0f6dac-a3ad-402c-8292-442f6561aaa2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CollaborationLossProfitSharingExpense_500f649c-142d-43d0-9804-8c15e3a2a892" xlink:href="incy-20230930.xsd#incy_CollaborationLossProfitSharingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_incy_CollaborationLossProfitSharingExpense_500f649c-142d-43d0-9804-8c15e3a2a892" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_a5f592b9-edf8-49f7-88a5-f73611f42078" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_a5f592b9-edf8-49f7-88a5-f73611f42078" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_2e92d6b6-864c-422b-9ac0-ed7a759bb892" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_2e92d6b6-864c-422b-9ac0-ed7a759bb892" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_d4b23583-48e1-4ab6-8323-04f51d400b7f" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_9ee00b7e-0efb-4529-b654-5b98807113cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_us-gaap_TypeOfArrangementAxis_9ee00b7e-0efb-4529-b654-5b98807113cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_9ee00b7e-0efb-4529-b654-5b98807113cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_9ee00b7e-0efb-4529-b654-5b98807113cb" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_9ee00b7e-0efb-4529-b654-5b98807113cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_f3d6fd4d-3cd8-47b7-b0ee-7525f5469aff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_9ee00b7e-0efb-4529-b654-5b98807113cb" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_f3d6fd4d-3cd8-47b7-b0ee-7525f5469aff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MorphosysAgMember_e82d2baa-51bc-4c8a-955d-144e6df64891" xlink:href="incy-20230930.xsd#incy_MorphosysAgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_f3d6fd4d-3cd8-47b7-b0ee-7525f5469aff" xlink:to="loc_incy_MorphosysAgMember_e82d2baa-51bc-4c8a-955d-144e6df64891" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_7d8d2d3e-56fa-4bdb-b56f-e04d40b0a830" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_dei_LegalEntityAxis_7d8d2d3e-56fa-4bdb-b56f-e04d40b0a830" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7d8d2d3e-56fa-4bdb-b56f-e04d40b0a830_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_7d8d2d3e-56fa-4bdb-b56f-e04d40b0a830" xlink:to="loc_dei_EntityDomain_7d8d2d3e-56fa-4bdb-b56f-e04d40b0a830_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_20c17afa-8da6-46cb-8c11-babb04ba15b7" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_7d8d2d3e-56fa-4bdb-b56f-e04d40b0a830" xlink:to="loc_dei_EntityDomain_20c17afa-8da6-46cb-8c11-babb04ba15b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_IncyteMember_fd8a3dbe-d3a6-4268-b36e-a56faa4f0bbd" xlink:href="incy-20230930.xsd#incy_IncyteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_20c17afa-8da6-46cb-8c11-babb04ba15b7" xlink:to="loc_incy_IncyteMember_fd8a3dbe-d3a6-4268-b36e-a56faa4f0bbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_373fbb29-9047-4b7a-ace5-ade1367ac59c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_srt_CounterpartyNameAxis_373fbb29-9047-4b7a-ace5-ade1367ac59c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_373fbb29-9047-4b7a-ace5-ade1367ac59c_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_373fbb29-9047-4b7a-ace5-ade1367ac59c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_373fbb29-9047-4b7a-ace5-ade1367ac59c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_d07d0358-02f7-4b8b-9d1e-6c4f0f912d3b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_373fbb29-9047-4b7a-ace5-ade1367ac59c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_d07d0358-02f7-4b8b-9d1e-6c4f0f912d3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MorphosysAgMember_2a6273f5-2297-415a-a295-959a57049bac" xlink:href="incy-20230930.xsd#incy_MorphosysAgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_d07d0358-02f7-4b8b-9d1e-6c4f0f912d3b" xlink:to="loc_incy_MorphosysAgMember_2a6273f5-2297-415a-a295-959a57049bac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneAxis_df178e43-feb3-4872-bc32-c875a06ae08b" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_incy_AchievementOfMilestoneAxis_df178e43-feb3-4872-bc32-c875a06ae08b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_df178e43-feb3-4872-bc32-c875a06ae08b_default" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_incy_AchievementOfMilestoneAxis_df178e43-feb3-4872-bc32-c875a06ae08b" xlink:to="loc_incy_AchievementOfMilestoneDomain_df178e43-feb3-4872-bc32-c875a06ae08b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_6b2a988f-fc4b-4b84-a148-ea878a20cc66" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_incy_AchievementOfMilestoneAxis_df178e43-feb3-4872-bc32-c875a06ae08b" xlink:to="loc_incy_AchievementOfMilestoneDomain_6b2a988f-fc4b-4b84-a148-ea878a20cc66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentAndRegulatoryMilestonesMember_b27ea80f-30ea-4119-903e-462b5dbfa3c3" xlink:href="incy-20230930.xsd#incy_DevelopmentAndRegulatoryMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_6b2a988f-fc4b-4b84-a148-ea878a20cc66" xlink:to="loc_incy_DevelopmentAndRegulatoryMilestonesMember_b27ea80f-30ea-4119-903e-462b5dbfa3c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CommercializationMilestonesMember_62db31fd-47bc-4fd7-88f8-3fb7d1cb7ca9" xlink:href="incy-20230930.xsd#incy_CommercializationMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_6b2a988f-fc4b-4b84-a148-ea878a20cc66" xlink:to="loc_incy_CommercializationMilestonesMember_62db31fd-47bc-4fd7-88f8-3fb7d1cb7ca9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_603ced5b-8ff8-4512-8067-49b615387670" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_srt_RangeAxis_603ced5b-8ff8-4512-8067-49b615387670" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_603ced5b-8ff8-4512-8067-49b615387670_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_603ced5b-8ff8-4512-8067-49b615387670" xlink:to="loc_srt_RangeMember_603ced5b-8ff8-4512-8067-49b615387670_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_737b38c9-1963-41b1-b6f6-d48428592cdb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_603ced5b-8ff8-4512-8067-49b615387670" xlink:to="loc_srt_RangeMember_737b38c9-1963-41b1-b6f6-d48428592cdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_3b12c17d-54e3-48a8-9a25-eff25b29d005" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_737b38c9-1963-41b1-b6f6-d48428592cdb" xlink:to="loc_srt_MaximumMember_3b12c17d-54e3-48a8-9a25-eff25b29d005" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_106e2846-d21b-48cd-a3c5-eaafa7c17483" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_106e2846-d21b-48cd-a3c5-eaafa7c17483" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_106e2846-d21b-48cd-a3c5-eaafa7c17483_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_106e2846-d21b-48cd-a3c5-eaafa7c17483" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_106e2846-d21b-48cd-a3c5-eaafa7c17483_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_297c7f30-c8cf-4485-877d-a954237fb985" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_106e2846-d21b-48cd-a3c5-eaafa7c17483" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_297c7f30-c8cf-4485-877d-a954237fb985" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_MorphosysAgMember_59104fa6-3978-44fe-a67b-7d72bbbc4322" xlink:href="incy-20230930.xsd#incy_MorphosysAgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_297c7f30-c8cf-4485-877d-a954237fb985" xlink:to="loc_incy_MorphosysAgMember_59104fa6-3978-44fe-a67b-7d72bbbc4322" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_34f6c066-8391-4bdf-8a35-a6f540c8984c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_srt_StatementGeographicalAxis_34f6c066-8391-4bdf-8a35-a6f540c8984c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_34f6c066-8391-4bdf-8a35-a6f540c8984c_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_34f6c066-8391-4bdf-8a35-a6f540c8984c" xlink:to="loc_srt_SegmentGeographicalDomain_34f6c066-8391-4bdf-8a35-a6f540c8984c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_fc4bf6d7-102b-4e99-b846-ffd28b78dff0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_34f6c066-8391-4bdf-8a35-a6f540c8984c" xlink:to="loc_srt_SegmentGeographicalDomain_fc4bf6d7-102b-4e99-b846-ffd28b78dff0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_431f5206-d882-4284-87fb-1059ef487929" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_fc4bf6d7-102b-4e99-b846-ffd28b78dff0" xlink:to="loc_country_US_431f5206-d882-4284-87fb-1059ef487929" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_27642a61-bbcb-499a-b189-937b95f3536b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_0bb02e03-fc4d-483d-b86d-cc9587376f42" xlink:to="loc_srt_ProductOrServiceAxis_27642a61-bbcb-499a-b189-937b95f3536b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_27642a61-bbcb-499a-b189-937b95f3536b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_27642a61-bbcb-499a-b189-937b95f3536b" xlink:to="loc_srt_ProductsAndServicesDomain_27642a61-bbcb-499a-b189-937b95f3536b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_0aaefa59-88b6-4641-bb13-234750c63031" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_27642a61-bbcb-499a-b189-937b95f3536b" xlink:to="loc_srt_ProductsAndServicesDomain_0aaefa59-88b6-4641-bb13-234750c63031" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_TafasitamabProductAndServiceMember_6c794606-e82d-4977-8149-8c4de27b8af9" xlink:href="incy-20230930.xsd#incy_TafasitamabProductAndServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_0aaefa59-88b6-4641-bb13-234750c63031" xlink:to="loc_incy_TafasitamabProductAndServiceMember_6c794606-e82d-4977-8149-8c4de27b8af9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/LicenseAgreementsSyndaxDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#LicenseAgreementsSyndaxDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/LicenseAgreementsSyndaxDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementPercentageOfFutureGlobalDevelopmentCostsFunded_6cbffa95-8a5d-433e-9773-8c8b9298b9be" xlink:href="incy-20230930.xsd#incy_LicenseAgreementPercentageOfFutureGlobalDevelopmentCostsFunded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_incy_LicenseAgreementPercentageOfFutureGlobalDevelopmentCostsFunded_6cbffa95-8a5d-433e-9773-8c8b9298b9be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementUpfrontPaymentAmountPaid_0d650ed7-d539-4c44-9cf4-2a360063483f" xlink:href="incy-20230930.xsd#incy_LicenseAgreementUpfrontPaymentAmountPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_incy_LicenseAgreementUpfrontPaymentAmountPaid_0d650ed7-d539-4c44-9cf4-2a360063483f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LicenseAgreementAdditionalMilestonePayments_9f343937-2fd7-481b-82d6-707e5215895f" xlink:href="incy-20230930.xsd#incy_LicenseAgreementAdditionalMilestonePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_incy_LicenseAgreementAdditionalMilestonePayments_9f343937-2fd7-481b-82d6-707e5215895f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_8955ec2b-01a1-41f3-88c0-92281e2515b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_8955ec2b-01a1-41f3-88c0-92281e2515b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermInvestments_598efa06-28be-4fdb-91db-67219ebb1954" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_us-gaap_LongTermInvestments_598efa06-28be-4fdb-91db-67219ebb1954" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_5e61ca16-3329-44ee-bfbc-fbd66511636c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_5e61ca16-3329-44ee-bfbc-fbd66511636c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_948a84d5-2d29-45c5-a5d3-5a69f181cb23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_948a84d5-2d29-45c5-a5d3-5a69f181cb23" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_87668942-0dc4-458a-8216-69309545bdaa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilities_87668942-0dc4-458a-8216-69309545bdaa" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_4f8fb134-c5a0-4c00-9b55-1472005dc2ef" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_93106060-25c4-431c-a1de-01c5c96c6e17" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_srt_StatementGeographicalAxis_93106060-25c4-431c-a1de-01c5c96c6e17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_93106060-25c4-431c-a1de-01c5c96c6e17_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_93106060-25c4-431c-a1de-01c5c96c6e17" xlink:to="loc_srt_SegmentGeographicalDomain_93106060-25c4-431c-a1de-01c5c96c6e17_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_6b6d8eb2-9b6b-42be-b65a-1410ec8fc635" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_93106060-25c4-431c-a1de-01c5c96c6e17" xlink:to="loc_srt_SegmentGeographicalDomain_6b6d8eb2-9b6b-42be-b65a-1410ec8fc635" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_be302b78-c30d-4e4d-9f8f-6f3fbd90be50" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_6b6d8eb2-9b6b-42be-b65a-1410ec8fc635" xlink:to="loc_country_US_be302b78-c30d-4e4d-9f8f-6f3fbd90be50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_b25daefe-a5ad-4452-adb8-36fb539185c8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_us-gaap_TypeOfArrangementAxis_b25daefe-a5ad-4452-adb8-36fb539185c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_b25daefe-a5ad-4452-adb8-36fb539185c8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_b25daefe-a5ad-4452-adb8-36fb539185c8" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_b25daefe-a5ad-4452-adb8-36fb539185c8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_875107be-5068-418c-a48f-f9b770eb4fab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_b25daefe-a5ad-4452-adb8-36fb539185c8" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_875107be-5068-418c-a48f-f9b770eb4fab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_SyndaxPharmaceuticalsIncMember_7de536c8-c5ec-4235-98b8-7bfbe8cdfbc2" xlink:href="incy-20230930.xsd#incy_SyndaxPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_875107be-5068-418c-a48f-f9b770eb4fab" xlink:to="loc_incy_SyndaxPharmaceuticalsIncMember_7de536c8-c5ec-4235-98b8-7bfbe8cdfbc2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_8e3f8576-0954-444d-849e-7a3935247abc" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_dei_LegalEntityAxis_8e3f8576-0954-444d-849e-7a3935247abc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_8e3f8576-0954-444d-849e-7a3935247abc_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_8e3f8576-0954-444d-849e-7a3935247abc" xlink:to="loc_dei_EntityDomain_8e3f8576-0954-444d-849e-7a3935247abc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_0cd4cc2e-a213-4086-b55a-d067bb22e919" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_8e3f8576-0954-444d-849e-7a3935247abc" xlink:to="loc_dei_EntityDomain_0cd4cc2e-a213-4086-b55a-d067bb22e919" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_IncyteMember_756f30d3-ef41-40d1-9e9c-b44a989d3262" xlink:href="incy-20230930.xsd#incy_IncyteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_0cd4cc2e-a213-4086-b55a-d067bb22e919" xlink:to="loc_incy_IncyteMember_756f30d3-ef41-40d1-9e9c-b44a989d3262" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_157e0e89-0bab-4ebb-9f28-b28499b2a3c7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_srt_CounterpartyNameAxis_157e0e89-0bab-4ebb-9f28-b28499b2a3c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_157e0e89-0bab-4ebb-9f28-b28499b2a3c7_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_157e0e89-0bab-4ebb-9f28-b28499b2a3c7" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_157e0e89-0bab-4ebb-9f28-b28499b2a3c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2de4278-60f7-4f81-bef4-5af6744dae5e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_157e0e89-0bab-4ebb-9f28-b28499b2a3c7" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2de4278-60f7-4f81-bef4-5af6744dae5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_SyndaxPharmaceuticalsIncMember_9de0bf38-5c69-4855-a7ce-5d0ac003ca69" xlink:href="incy-20230930.xsd#incy_SyndaxPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c2de4278-60f7-4f81-bef4-5af6744dae5e" xlink:to="loc_incy_SyndaxPharmaceuticalsIncMember_9de0bf38-5c69-4855-a7ce-5d0ac003ca69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneAxis_7bc0b6ba-d25a-40d6-99ac-aa93942f9767" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_incy_AchievementOfMilestoneAxis_7bc0b6ba-d25a-40d6-99ac-aa93942f9767" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_7bc0b6ba-d25a-40d6-99ac-aa93942f9767_default" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_incy_AchievementOfMilestoneAxis_7bc0b6ba-d25a-40d6-99ac-aa93942f9767" xlink:to="loc_incy_AchievementOfMilestoneDomain_7bc0b6ba-d25a-40d6-99ac-aa93942f9767_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AchievementOfMilestoneDomain_f4547f2a-d0a7-4b08-9f1f-18f54a33f727" xlink:href="incy-20230930.xsd#incy_AchievementOfMilestoneDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_incy_AchievementOfMilestoneAxis_7bc0b6ba-d25a-40d6-99ac-aa93942f9767" xlink:to="loc_incy_AchievementOfMilestoneDomain_f4547f2a-d0a7-4b08-9f1f-18f54a33f727" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_DevelopmentAndRegulatoryMilestonesMember_234fa231-cca5-4a29-84b2-db6370bd8902" xlink:href="incy-20230930.xsd#incy_DevelopmentAndRegulatoryMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_f4547f2a-d0a7-4b08-9f1f-18f54a33f727" xlink:to="loc_incy_DevelopmentAndRegulatoryMilestonesMember_234fa231-cca5-4a29-84b2-db6370bd8902" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_CommercializationMilestonesMember_2ebfa04d-1549-44f7-8a85-e1fc0dec967e" xlink:href="incy-20230930.xsd#incy_CommercializationMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_incy_AchievementOfMilestoneDomain_f4547f2a-d0a7-4b08-9f1f-18f54a33f727" xlink:to="loc_incy_CommercializationMilestonesMember_2ebfa04d-1549-44f7-8a85-e1fc0dec967e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_44528b4e-d156-497d-ad18-d05561f8b13f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_srt_RangeAxis_44528b4e-d156-497d-ad18-d05561f8b13f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_44528b4e-d156-497d-ad18-d05561f8b13f_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_44528b4e-d156-497d-ad18-d05561f8b13f" xlink:to="loc_srt_RangeMember_44528b4e-d156-497d-ad18-d05561f8b13f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_78629db3-5fed-4b01-be19-f2dd1128d566" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_44528b4e-d156-497d-ad18-d05561f8b13f" xlink:to="loc_srt_RangeMember_78629db3-5fed-4b01-be19-f2dd1128d566" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d77421c4-02b7-425c-bfcb-ad1cd98260da" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_78629db3-5fed-4b01-be19-f2dd1128d566" xlink:to="loc_srt_MaximumMember_d77421c4-02b7-425c-bfcb-ad1cd98260da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_bd5893fa-4caa-4fc2-b756-bbf957304954" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_bd5893fa-4caa-4fc2-b756-bbf957304954" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_bd5893fa-4caa-4fc2-b756-bbf957304954_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_bd5893fa-4caa-4fc2-b756-bbf957304954" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_bd5893fa-4caa-4fc2-b756-bbf957304954_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_486e1846-58b7-4f8c-9b4f-98aa0308081e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_bd5893fa-4caa-4fc2-b756-bbf957304954" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_486e1846-58b7-4f8c-9b4f-98aa0308081e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_InvestmentInSyndaxPharmaceuticalsIncMember_86370e70-af97-4023-a20a-ce22766e7d37" xlink:href="incy-20230930.xsd#incy_InvestmentInSyndaxPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_486e1846-58b7-4f8c-9b4f-98aa0308081e" xlink:to="loc_incy_InvestmentInSyndaxPharmaceuticalsIncMember_86370e70-af97-4023-a20a-ce22766e7d37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_e5ac1036-01f5-4d74-b66c-b495e2403b82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_8a1920b9-3fbf-4d2d-ae48-330de3ff5b69" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_e5ac1036-01f5-4d74-b66c-b495e2403b82" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_e5ac1036-01f5-4d74-b66c-b495e2403b82_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_e5ac1036-01f5-4d74-b66c-b495e2403b82" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_e5ac1036-01f5-4d74-b66c-b495e2403b82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_e2c9d587-d32c-40fc-8eb1-61a4f3b77989" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_e5ac1036-01f5-4d74-b66c-b495e2403b82" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_e2c9d587-d32c-40fc-8eb1-61a4f3b77989" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_8d4c1c07-ba62-41db-b2a6-601d9ed759b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_e2c9d587-d32c-40fc-8eb1-61a4f3b77989" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_8d4c1c07-ba62-41db-b2a6-601d9ed759b0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/PropertyandEquipmentnetPropertyandequipmentnetDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#PropertyandEquipmentnetPropertyandequipmentnetDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/PropertyandEquipmentnetPropertyandequipmentnetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_903dab21-d28e-4e7e-8e23-066f320ca278" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_66caf9b4-48c1-49ea-a434-2b455cbb7366" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_903dab21-d28e-4e7e-8e23-066f320ca278" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_66caf9b4-48c1-49ea-a434-2b455cbb7366" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_5edd0f9c-f40e-4e0d-a359-ff67a28cd3e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_903dab21-d28e-4e7e-8e23-066f320ca278" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_5edd0f9c-f40e-4e0d-a359-ff67a28cd3e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_0a29f994-c426-4a84-8236-9335457fc915" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_903dab21-d28e-4e7e-8e23-066f320ca278" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_0a29f994-c426-4a84-8236-9335457fc915" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_38acf6e3-603f-4a8a-9c2b-4e6489a6db7a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_903dab21-d28e-4e7e-8e23-066f320ca278" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_38acf6e3-603f-4a8a-9c2b-4e6489a6db7a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b8754839-2fec-4f2e-aa80-6c2902a0bbce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_38acf6e3-603f-4a8a-9c2b-4e6489a6db7a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b8754839-2fec-4f2e-aa80-6c2902a0bbce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b8754839-2fec-4f2e-aa80-6c2902a0bbce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b8754839-2fec-4f2e-aa80-6c2902a0bbce" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_b8754839-2fec-4f2e-aa80-6c2902a0bbce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_b8754839-2fec-4f2e-aa80-6c2902a0bbce" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OfficeEquipmentMember_d0a2a7f8-b91d-4514-947a-5f0c433ed773" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OfficeEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:to="loc_us-gaap_OfficeEquipmentMember_d0a2a7f8-b91d-4514-947a-5f0c433ed773" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember_f727aa87-0d67-4df0-91fd-a3cce95e4049" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:to="loc_us-gaap_EquipmentMember_f727aa87-0d67-4df0-91fd-a3cce95e4049" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_40902b8b-f1e4-41d6-aa8e-4dd2fedee719" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:to="loc_us-gaap_ComputerEquipmentMember_40902b8b-f1e4-41d6-aa8e-4dd2fedee719" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember_eb4551eb-3d39-4b1b-b1f1-308c64dfe492" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:to="loc_us-gaap_LandMember_eb4551eb-3d39-4b1b-b1f1-308c64dfe492" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_BuildingAndLeaseholdImprovementsMember_7ccdaf21-cf9a-4673-b178-73f773de8e57" xlink:href="incy-20230930.xsd#incy_BuildingAndLeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:to="loc_incy_BuildingAndLeaseholdImprovementsMember_7ccdaf21-cf9a-4673-b178-73f773de8e57" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_OperatingLeaseRightOfUseAssetsMember_876f6647-5c57-43ca-802b-e2d98a4af024" xlink:href="incy-20230930.xsd#incy_OperatingLeaseRightOfUseAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:to="loc_incy_OperatingLeaseRightOfUseAssetsMember_876f6647-5c57-43ca-802b-e2d98a4af024" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_f35be6df-8813-4dd4-a611-3be273669511" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5d2cd747-7089-4b52-93e5-ce512d2d4727" xlink:to="loc_us-gaap_ConstructionInProgressMember_f35be6df-8813-4dd4-a611-3be273669511" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/StockCompensationNarrativeDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#StockCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/StockCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_329c60a0-3271-4891-a06f-e2e1ff7a4e20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_329c60a0-3271-4891-a06f-e2e1ff7a4e20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_57d24779-ebaf-44c7-8fa5-444fbd1018ad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_57d24779-ebaf-44c7-8fa5-444fbd1018ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_1890b7ca-febf-41cd-b7e5-6d216c7883b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_1890b7ca-febf-41cd-b7e5-6d216c7883b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_fbabf988-7330-40f5-af22-5419d99f63f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_fbabf988-7330-40f5-af22-5419d99f63f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_124a3df2-d251-4273-bd40-992144ebb3b2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_124a3df2-d251-4273-bd40-992144ebb3b2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesPerRestrictedStockUnits_a1dbc662-5183-4f58-bafa-ee9d0ba60693" xlink:href="incy-20230930.xsd#incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesPerRestrictedStockUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesPerRestrictedStockUnits_a1dbc662-5183-4f58-bafa-ee9d0ba60693" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedAnnualizedForfeitureRate_0e4dec33-a811-4cd3-8df4-cbe8b4898215" xlink:href="incy-20230930.xsd#incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedAnnualizedForfeitureRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedAnnualizedForfeitureRate_0e4dec33-a811-4cd3-8df4-cbe8b4898215" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0fe182f4-c97e-4fd2-a8db-04d36edbd740" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0fe182f4-c97e-4fd2-a8db-04d36edbd740" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_0094f4eb-0fe9-4854-8036-3f8f76f81ee7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_0094f4eb-0fe9-4854-8036-3f8f76f81ee7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5f706fb4-12cb-49e3-ae2a-84a3f95733ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_15735533-4f9e-448f-910b-7e3e89e05075" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5f706fb4-12cb-49e3-ae2a-84a3f95733ca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_f7846948-4b79-4b7f-8411-970119eaa86c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5f706fb4-12cb-49e3-ae2a-84a3f95733ca" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_f7846948-4b79-4b7f-8411-970119eaa86c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_f7846948-4b79-4b7f-8411-970119eaa86c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_f7846948-4b79-4b7f-8411-970119eaa86c" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_f7846948-4b79-4b7f-8411-970119eaa86c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_e9f59c66-9921-4a02-a76e-19a0bc68b0c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_f7846948-4b79-4b7f-8411-970119eaa86c" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_e9f59c66-9921-4a02-a76e-19a0bc68b0c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_2041c2a7-9b62-4112-8f4e-94f2d2931ccc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_e9f59c66-9921-4a02-a76e-19a0bc68b0c0" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_2041c2a7-9b62-4112-8f4e-94f2d2931ccc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_25454883-46bf-4175-bf0a-f9497f6cce2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_e9f59c66-9921-4a02-a76e-19a0bc68b0c0" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_25454883-46bf-4175-bf0a-f9497f6cce2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_646b6ebe-a5db-477d-903a-b144d55fa0ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_e9f59c66-9921-4a02-a76e-19a0bc68b0c0" xlink:to="loc_us-gaap_CostOfSalesMember_646b6ebe-a5db-477d-903a-b144d55fa0ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_e03caa9e-e37d-4c11-bc25-355aa57f4895" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5f706fb4-12cb-49e3-ae2a-84a3f95733ca" xlink:to="loc_us-gaap_AwardTypeAxis_e03caa9e-e37d-4c11-bc25-355aa57f4895" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e03caa9e-e37d-4c11-bc25-355aa57f4895_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_e03caa9e-e37d-4c11-bc25-355aa57f4895" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e03caa9e-e37d-4c11-bc25-355aa57f4895_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a409e124-7f19-4ad3-9136-239bec94dff7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_e03caa9e-e37d-4c11-bc25-355aa57f4895" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a409e124-7f19-4ad3-9136-239bec94dff7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_95de3686-2218-4269-9478-d0d1cc4e5cce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a409e124-7f19-4ad3-9136-239bec94dff7" xlink:to="loc_us-gaap_EmployeeStockOptionMember_95de3686-2218-4269-9478-d0d1cc4e5cce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_9f502a73-6b7d-4e28-a1da-e1208049dfbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a409e124-7f19-4ad3-9136-239bec94dff7" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_9f502a73-6b7d-4e28-a1da-e1208049dfbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_b7ef5cab-1e89-4bd1-8c27-624ab8c2f0ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a409e124-7f19-4ad3-9136-239bec94dff7" xlink:to="loc_us-gaap_PerformanceSharesMember_b7ef5cab-1e89-4bd1-8c27-624ab8c2f0ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_94951029-494b-43ff-942e-5b33b63c9faa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5f706fb4-12cb-49e3-ae2a-84a3f95733ca" xlink:to="loc_us-gaap_VestingAxis_94951029-494b-43ff-942e-5b33b63c9faa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_94951029-494b-43ff-942e-5b33b63c9faa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_94951029-494b-43ff-942e-5b33b63c9faa" xlink:to="loc_us-gaap_VestingDomain_94951029-494b-43ff-942e-5b33b63c9faa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_b9b37b18-e768-4e88-b3ee-03499a979734" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_94951029-494b-43ff-942e-5b33b63c9faa" xlink:to="loc_us-gaap_VestingDomain_b9b37b18-e768-4e88-b3ee-03499a979734" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_ccff771c-b396-4a44-87c0-8888bb01635e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_b9b37b18-e768-4e88-b3ee-03499a979734" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_ccff771c-b396-4a44-87c0-8888bb01635e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_a93b5503-1764-47ab-854f-37d23bee3ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_b9b37b18-e768-4e88-b3ee-03499a979734" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_a93b5503-1764-47ab-854f-37d23bee3ecd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_dce49887-ee5f-4625-bc75-8da7fab33fc1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5f706fb4-12cb-49e3-ae2a-84a3f95733ca" xlink:to="loc_srt_RangeAxis_dce49887-ee5f-4625-bc75-8da7fab33fc1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_dce49887-ee5f-4625-bc75-8da7fab33fc1_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_dce49887-ee5f-4625-bc75-8da7fab33fc1" xlink:to="loc_srt_RangeMember_dce49887-ee5f-4625-bc75-8da7fab33fc1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_28895835-68e5-410f-93f6-a9ecea9e8dfd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_dce49887-ee5f-4625-bc75-8da7fab33fc1" xlink:to="loc_srt_RangeMember_28895835-68e5-410f-93f6-a9ecea9e8dfd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_af4cd933-e2e4-4ff0-aa20-18dff72addee" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_28895835-68e5-410f-93f6-a9ecea9e8dfd" xlink:to="loc_srt_MinimumMember_af4cd933-e2e4-4ff0-aa20-18dff72addee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_685d0f9a-40c6-450e-9c38-e60b68240182" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_28895835-68e5-410f-93f6-a9ecea9e8dfd" xlink:to="loc_srt_MaximumMember_685d0f9a-40c6-450e-9c38-e60b68240182" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/StockCompensationValuationassumptionsusedforvalueofstockcompensationgrantedDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#StockCompensationValuationassumptionsusedforvalueofstockcompensationgrantedDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/StockCompensationValuationassumptionsusedforvalueofstockcompensationgrantedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_33778e02-db4d-4862-8b1b-9d1191a3c320" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_659ad8be-ac89-48d4-9692-f4993f68b426" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_33778e02-db4d-4862-8b1b-9d1191a3c320" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_659ad8be-ac89-48d4-9692-f4993f68b426" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_219e1fae-bfa7-4f71-8313-9543541d7408" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_659ad8be-ac89-48d4-9692-f4993f68b426" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_219e1fae-bfa7-4f71-8313-9543541d7408" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_f8808355-be07-4f79-851d-82e3bd34b863" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_659ad8be-ac89-48d4-9692-f4993f68b426" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_f8808355-be07-4f79-851d-82e3bd34b863" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_7f1b791b-3e21-495f-b8e4-65e96adc7479" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_659ad8be-ac89-48d4-9692-f4993f68b426" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_7f1b791b-3e21-495f-b8e4-65e96adc7479" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8d77040e-b43b-4ef0-acd6-2ea88cdffd4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_659ad8be-ac89-48d4-9692-f4993f68b426" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_8d77040e-b43b-4ef0-acd6-2ea88cdffd4f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c3123325-4c7d-41e1-95bb-c341e6d09ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_33778e02-db4d-4862-8b1b-9d1191a3c320" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c3123325-4c7d-41e1-95bb-c341e6d09ec2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_10d6e01f-2af5-4aa3-9eab-03136202f63a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c3123325-4c7d-41e1-95bb-c341e6d09ec2" xlink:to="loc_us-gaap_AwardTypeAxis_10d6e01f-2af5-4aa3-9eab-03136202f63a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10d6e01f-2af5-4aa3-9eab-03136202f63a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_10d6e01f-2af5-4aa3-9eab-03136202f63a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10d6e01f-2af5-4aa3-9eab-03136202f63a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8fac5a1e-3069-40b2-aa20-60bba8c5ff7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_10d6e01f-2af5-4aa3-9eab-03136202f63a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8fac5a1e-3069-40b2-aa20-60bba8c5ff7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_44d621b2-3ce7-4c81-a29d-88bb27e6eb5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8fac5a1e-3069-40b2-aa20-60bba8c5ff7e" xlink:to="loc_us-gaap_EmployeeStockOptionMember_44d621b2-3ce7-4c81-a29d-88bb27e6eb5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_5b4e4345-e0fe-4184-9975-ea49003d027e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c3123325-4c7d-41e1-95bb-c341e6d09ec2" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_5b4e4345-e0fe-4184-9975-ea49003d027e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_5b4e4345-e0fe-4184-9975-ea49003d027e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_5b4e4345-e0fe-4184-9975-ea49003d027e" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_5b4e4345-e0fe-4184-9975-ea49003d027e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_8acf01bc-4e4b-45c8-a8aa-4ed85421b215" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_5b4e4345-e0fe-4184-9975-ea49003d027e" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_8acf01bc-4e4b-45c8-a8aa-4ed85421b215" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_c9ac852e-49e8-4f88-b44c-51b3fb669fcd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_8acf01bc-4e4b-45c8-a8aa-4ed85421b215" xlink:to="loc_us-gaap_EmployeeStockMember_c9ac852e-49e8-4f88-b44c-51b3fb669fcd" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/StockCompensationOptionactivityunderthe2010stockplanDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#StockCompensationOptionactivityunderthe2010stockplanDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/StockCompensationOptionactivityunderthe2010stockplanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4665c592-89f0-49ab-a40f-a8c211389c0f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_944cfa33-f921-4b6e-8b9b-e4632079a2cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4665c592-89f0-49ab-a40f-a8c211389c0f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_944cfa33-f921-4b6e-8b9b-e4632079a2cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_380ded71-0088-4a24-8ace-36ca1e7933a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_944cfa33-f921-4b6e-8b9b-e4632079a2cf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_380ded71-0088-4a24-8ace-36ca1e7933a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_2ce6c4a0-b48f-43dd-9a75-9f3f3f8fe55c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_944cfa33-f921-4b6e-8b9b-e4632079a2cf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_2ce6c4a0-b48f-43dd-9a75-9f3f3f8fe55c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_39115887-2e83-403b-aa25-06b1703864d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_944cfa33-f921-4b6e-8b9b-e4632079a2cf" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_39115887-2e83-403b-aa25-06b1703864d5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_a5564625-fb2d-462b-9f3f-db5111581988" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_944cfa33-f921-4b6e-8b9b-e4632079a2cf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_a5564625-fb2d-462b-9f3f-db5111581988" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_b57d8532-1130-45bb-9cff-66bd622ee3f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_50e586cb-dad8-4bdc-ab9d-3fec758865cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4665c592-89f0-49ab-a40f-a8c211389c0f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_50e586cb-dad8-4bdc-ab9d-3fec758865cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_f1125c99-099a-40ce-aa17-b45acd199b76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_50e586cb-dad8-4bdc-ab9d-3fec758865cb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_f1125c99-099a-40ce-aa17-b45acd199b76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_a5435be1-2beb-4adf-aeeb-773b264d0b85" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_50e586cb-dad8-4bdc-ab9d-3fec758865cb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_a5435be1-2beb-4adf-aeeb-773b264d0b85" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_c83b91a1-4853-40a9-817c-658d296fd09a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_50e586cb-dad8-4bdc-ab9d-3fec758865cb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_c83b91a1-4853-40a9-817c-658d296fd09a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_c6bf6d74-9f0f-4f0d-9068-06e1f1012c5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_50e586cb-dad8-4bdc-ab9d-3fec758865cb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_c6bf6d74-9f0f-4f0d-9068-06e1f1012c5c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_1e8724da-e25e-484c-88b3-ade059829a4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_10400b09-c04c-4f28-956c-2d5bc69d7cfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4665c592-89f0-49ab-a40f-a8c211389c0f" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_10400b09-c04c-4f28-956c-2d5bc69d7cfc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_df1d210e-5278-4ad1-b6f6-89bd57711207" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_10400b09-c04c-4f28-956c-2d5bc69d7cfc" xlink:to="loc_us-gaap_AwardTypeAxis_df1d210e-5278-4ad1-b6f6-89bd57711207" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_df1d210e-5278-4ad1-b6f6-89bd57711207_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_df1d210e-5278-4ad1-b6f6-89bd57711207" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_df1d210e-5278-4ad1-b6f6-89bd57711207_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_185e2b82-0389-4c3f-9ef4-9459e66a08f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_df1d210e-5278-4ad1-b6f6-89bd57711207" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_185e2b82-0389-4c3f-9ef4-9459e66a08f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_06736aee-0283-4c78-8577-5697a8bc581e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_185e2b82-0389-4c3f-9ef4-9459e66a08f7" xlink:to="loc_us-gaap_EmployeeStockOptionMember_06736aee-0283-4c78-8577-5697a8bc581e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/StockCompensationRSUawardandPSUactivityunderthe2010stockplanDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#StockCompensationRSUawardandPSUactivityunderthe2010stockplanDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/StockCompensationRSUawardandPSUactivityunderthe2010stockplanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9b354ce7-5079-44a2-aa40-a59572b90da8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b1223e2d-d0a2-4742-8fc4-7ad64a416304" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9b354ce7-5079-44a2-aa40-a59572b90da8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b1223e2d-d0a2-4742-8fc4-7ad64a416304" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_83d494ff-b460-4185-b515-24ea3813ebbb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b1223e2d-d0a2-4742-8fc4-7ad64a416304" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_83d494ff-b460-4185-b515-24ea3813ebbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_a6e53a61-0b7d-4a26-be92-28eff67fee64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b1223e2d-d0a2-4742-8fc4-7ad64a416304" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_a6e53a61-0b7d-4a26-be92-28eff67fee64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedInPeriod_750918fc-3ce3-487f-926f-f85421dea8c3" xlink:href="incy-20230930.xsd#incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b1223e2d-d0a2-4742-8fc4-7ad64a416304" xlink:to="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedInPeriod_750918fc-3ce3-487f-926f-f85421dea8c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_9a15589e-8906-4744-8e82-047d12677d29" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b1223e2d-d0a2-4742-8fc4-7ad64a416304" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_9a15589e-8906-4744-8e82-047d12677d29" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_885d8b8a-add5-4412-a3c3-9d80b8c7c297" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_fd4d7dff-2723-440e-ae89-c929c0f1b983" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9b354ce7-5079-44a2-aa40-a59572b90da8" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_fd4d7dff-2723-440e-ae89-c929c0f1b983" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_e89e9c1e-53f9-41f5-93ba-47fabdf9d27d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_fd4d7dff-2723-440e-ae89-c929c0f1b983" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_e89e9c1e-53f9-41f5-93ba-47fabdf9d27d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodIntrinsicValue_f400388f-512e-4668-b529-fc3aca360eb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_fd4d7dff-2723-440e-ae89-c929c0f1b983" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodIntrinsicValue_f400388f-512e-4668-b529-fc3aca360eb0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedIntrinsicValue_b0bf9022-245b-4dda-ad97-ee49ecdcea80" xlink:href="incy-20230930.xsd#incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_fd4d7dff-2723-440e-ae89-c929c0f1b983" xlink:to="loc_incy_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedIntrinsicValue_b0bf9022-245b-4dda-ad97-ee49ecdcea80" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresIntrinsicValue_dd46afd9-53c5-4106-9646-0698db259245" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_fd4d7dff-2723-440e-ae89-c929c0f1b983" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresIntrinsicValue_dd46afd9-53c5-4106-9646-0698db259245" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_8d79ecc9-7262-4b89-9501-689091f55c12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_78ea1928-7df2-4292-a5ec-7a1e12752bfd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9b354ce7-5079-44a2-aa40-a59572b90da8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_78ea1928-7df2-4292-a5ec-7a1e12752bfd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_2122f93a-f326-4a89-973a-ae67b667a794" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_78ea1928-7df2-4292-a5ec-7a1e12752bfd" xlink:to="loc_us-gaap_AwardTypeAxis_2122f93a-f326-4a89-973a-ae67b667a794" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2122f93a-f326-4a89-973a-ae67b667a794_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2122f93a-f326-4a89-973a-ae67b667a794" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2122f93a-f326-4a89-973a-ae67b667a794_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5653aa28-2f12-48bd-b236-7696d5dad7a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2122f93a-f326-4a89-973a-ae67b667a794" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5653aa28-2f12-48bd-b236-7696d5dad7a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_210d30fb-f618-4693-b535-897a90a0d8e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5653aa28-2f12-48bd-b236-7696d5dad7a1" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_210d30fb-f618-4693-b535-897a90a0d8e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_d8c3cf18-072f-4164-88c6-25116c4bd35f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5653aa28-2f12-48bd-b236-7696d5dad7a1" xlink:to="loc_us-gaap_PerformanceSharesMember_d8c3cf18-072f-4164-88c6-25116c4bd35f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/NetIncomePerShareAntidilutivesecuritiesDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#NetIncomePerShareAntidilutivesecuritiesDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/NetIncomePerShareAntidilutivesecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicLineItems_3a05a80a-4b17-4c9c-8fbc-bde2028fa393" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasicLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract_b27fd108-5625-4832-ad03-61e8cf72e336" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_3a05a80a-4b17-4c9c-8fbc-bde2028fa393" xlink:to="loc_us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract_b27fd108-5625-4832-ad03-61e8cf72e336" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_5594049f-cfe6-4140-8f88-67cbf9cdfccd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract_b27fd108-5625-4832-ad03-61e8cf72e336" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_5594049f-cfe6-4140-8f88-67cbf9cdfccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_3c3604a9-d22a-49b6-9164-f3a389a3d92c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_3a05a80a-4b17-4c9c-8fbc-bde2028fa393" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_3c3604a9-d22a-49b6-9164-f3a389a3d92c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_f4ad887b-2768-4a43-9924-75024b5997e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_3c3604a9-d22a-49b6-9164-f3a389a3d92c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_f4ad887b-2768-4a43-9924-75024b5997e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f4ad887b-2768-4a43-9924-75024b5997e7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_f4ad887b-2768-4a43-9924-75024b5997e7" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f4ad887b-2768-4a43-9924-75024b5997e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_83fa2ab9-3169-45d6-838b-d7bd845c47a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_f4ad887b-2768-4a43-9924-75024b5997e7" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_83fa2ab9-3169-45d6-838b-d7bd845c47a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_b8dacd6b-4db1-47b2-b2b3-9e4859905f6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_83fa2ab9-3169-45d6-838b-d7bd845c47a7" xlink:to="loc_us-gaap_StockCompensationPlanMember_b8dacd6b-4db1-47b2-b2b3-9e4859905f6e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.incyte.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="incy-20230930.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.incyte.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_b6ef6ca9-a45c-4e35-b636-880bfe3e7fbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_95a5318c-3492-4b62-9f27-3c014dbbfffd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b6ef6ca9-a45c-4e35-b636-880bfe3e7fbc" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_95a5318c-3492-4b62-9f27-3c014dbbfffd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_LossContingencesGrossToNetDeductionPercentage_e2eaa6d5-ea5f-44b1-b488-bb025d9e2f8f" xlink:href="incy-20230930.xsd#incy_LossContingencesGrossToNetDeductionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_b6ef6ca9-a45c-4e35-b636-880bfe3e7fbc" xlink:to="loc_incy_LossContingencesGrossToNetDeductionPercentage_e2eaa6d5-ea5f-44b1-b488-bb025d9e2f8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_5a653817-0acb-40db-91aa-13262482f88c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_b6ef6ca9-a45c-4e35-b636-880bfe3e7fbc" xlink:to="loc_us-gaap_LossContingenciesTable_5a653817-0acb-40db-91aa-13262482f88c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_f7901de8-7f22-44f6-a4c5-5c37f88c7866" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_5a653817-0acb-40db-91aa-13262482f88c" xlink:to="loc_srt_ProductOrServiceAxis_f7901de8-7f22-44f6-a4c5-5c37f88c7866" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f7901de8-7f22-44f6-a4c5-5c37f88c7866_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_f7901de8-7f22-44f6-a4c5-5c37f88c7866" xlink:to="loc_srt_ProductsAndServicesDomain_f7901de8-7f22-44f6-a4c5-5c37f88c7866_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3a6b5094-aae5-496d-93ba-803cef7e0461" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_f7901de8-7f22-44f6-a4c5-5c37f88c7866" xlink:to="loc_srt_ProductsAndServicesDomain_3a6b5094-aae5-496d-93ba-803cef7e0461" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_JAKAFIMember_642edb5a-345a-4d21-b9fd-a9fa687be3ad" xlink:href="incy-20230930.xsd#incy_JAKAFIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3a6b5094-aae5-496d-93ba-803cef7e0461" xlink:to="loc_incy_JAKAFIMember_642edb5a-345a-4d21-b9fd-a9fa687be3ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_f9c5c4c0-8163-4759-a57b-5c101298db84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_5a653817-0acb-40db-91aa-13262482f88c" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_f9c5c4c0-8163-4759-a57b-5c101298db84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_f9c5c4c0-8163-4759-a57b-5c101298db84_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_f9c5c4c0-8163-4759-a57b-5c101298db84" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_f9c5c4c0-8163-4759-a57b-5c101298db84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_2f5ec402-042c-4bc3-9022-48943d08cd40" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_f9c5c4c0-8163-4759-a57b-5c101298db84" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_2f5ec402-042c-4bc3-9022-48943d08cd40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_AccruedAndOtherCurrentLiabilitiesMember_c80c0162-afe4-46d4-a9e1-2ae47c288715" xlink:href="incy-20230930.xsd#incy_AccruedAndOtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_2f5ec402-042c-4bc3-9022-48943d08cd40" xlink:to="loc_incy_AccruedAndOtherCurrentLiabilitiesMember_c80c0162-afe4-46d4-a9e1-2ae47c288715" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_d7a76e7a-9625-4bcd-b24a-23b6211e0382" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_5a653817-0acb-40db-91aa-13262482f88c" xlink:to="loc_srt_LitigationCaseAxis_d7a76e7a-9625-4bcd-b24a-23b6211e0382" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_d7a76e7a-9625-4bcd-b24a-23b6211e0382_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_d7a76e7a-9625-4bcd-b24a-23b6211e0382" xlink:to="loc_srt_LitigationCaseTypeDomain_d7a76e7a-9625-4bcd-b24a-23b6211e0382_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_85de0c03-53c4-42b8-a74e-22ada198b33f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_d7a76e7a-9625-4bcd-b24a-23b6211e0382" xlink:to="loc_srt_LitigationCaseTypeDomain_85de0c03-53c4-42b8-a74e-22ada198b33f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_USCentersForMedicareAndMedicaidServicesMember_64654d47-ceb4-49ae-851c-23c1bb5409cb" xlink:href="incy-20230930.xsd#incy_USCentersForMedicareAndMedicaidServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_85de0c03-53c4-42b8-a74e-22ada198b33f" xlink:to="loc_incy_USCentersForMedicareAndMedicaidServicesMember_64654d47-ceb4-49ae-851c-23c1bb5409cb" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_PerformanceSharesMember" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_VijayIyengarMember_f68f2393-69f1-4896-b9f1-275871a20ff7" xlink:href="incy-20230930.xsd#incy_VijayIyengarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_incy_VijayIyengarMember_f68f2393-69f1-4896-b9f1-275871a20ff7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_incy_ThomasTrayMember_3a26deea-77c5-4c0f-972c-46b2d941e5df" xlink:href="incy-20230930.xsd#incy_ThomasTrayMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_incy_ThomasTrayMember_3a26deea-77c5-4c0f-972c-46b2d941e5df" xlink:type="arc" order="3"/>
  </link:definitionLink>
</link:linkbase>
