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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:f271a251-e32e-4d48-8c5c-0126177ad711,g:05008717-6b25-4d7b-a1b7-0560901d8c89-->
<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.busey.com/role/Cover" xlink:type="simple" xlink:href="buse-20250722.xsd#Cover"/>
  <link:definitionLink xlink:role="http://www.busey.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_2966ef60-b806-4e26-99fe-ef51e1a6d0ae" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_DocumentInformationTable_2966ef60-b806-4e26-99fe-ef51e1a6d0ae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_7481a881-4d1d-4a96-a42d-806f2c1fe28f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_2966ef60-b806-4e26-99fe-ef51e1a6d0ae" xlink:to="loc_us-gaap_StatementClassOfStockAxis_7481a881-4d1d-4a96-a42d-806f2c1fe28f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7481a881-4d1d-4a96-a42d-806f2c1fe28f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7481a881-4d1d-4a96-a42d-806f2c1fe28f" xlink:to="loc_us-gaap_ClassOfStockDomain_7481a881-4d1d-4a96-a42d-806f2c1fe28f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_eecd4cfa-a209-463a-ac7a-eba1809933e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7481a881-4d1d-4a96-a42d-806f2c1fe28f" xlink:to="loc_us-gaap_ClassOfStockDomain_eecd4cfa-a209-463a-ac7a-eba1809933e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_buse_CommonStock0.001ParValueMember_f6c41146-a9b9-4472-b264-ef17acfb4a12" xlink:href="buse-20250722.xsd#buse_CommonStock0.001ParValueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_eecd4cfa-a209-463a-ac7a-eba1809933e9" xlink:to="loc_buse_CommonStock0.001ParValueMember_f6c41146-a9b9-4472-b264-ef17acfb4a12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_buse_DepositarySharesEachRepresentingA140thInterestInAShareOf8.25FixedRateSeriesBNonCumulativePerpetualPreferredStock0.001ParValueMember_15ad60fc-0831-4f42-a857-2a5b5c38bd0c" xlink:href="buse-20250722.xsd#buse_DepositarySharesEachRepresentingA140thInterestInAShareOf8.25FixedRateSeriesBNonCumulativePerpetualPreferredStock0.001ParValueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_eecd4cfa-a209-463a-ac7a-eba1809933e9" xlink:to="loc_buse_DepositarySharesEachRepresentingA140thInterestInAShareOf8.25FixedRateSeriesBNonCumulativePerpetualPreferredStock0.001ParValueMember_15ad60fc-0831-4f42-a857-2a5b5c38bd0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_0e8addbf-3986-4d4a-837f-5a54e8e21d09" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_DocumentType_0e8addbf-3986-4d4a-837f-5a54e8e21d09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_f4a8019f-2821-4f11-be21-698554f551a6" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_DocumentPeriodEndDate_f4a8019f-2821-4f11-be21-698554f551a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_46341c31-023c-47ff-b6cd-95011f19d932" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityRegistrantName_46341c31-023c-47ff-b6cd-95011f19d932" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_9a7a6088-3263-46de-8ab2-f5e0c5ccb2ec" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityIncorporationStateCountryCode_9a7a6088-3263-46de-8ab2-f5e0c5ccb2ec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_2273ef3d-b7a9-4202-8f6d-15d26b63f570" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityFileNumber_2273ef3d-b7a9-4202-8f6d-15d26b63f570" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_da869a72-77fc-4ac5-b27b-8522a19517a2" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityTaxIdentificationNumber_da869a72-77fc-4ac5-b27b-8522a19517a2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_7e9da897-a93c-4f4d-a0cb-2c66fa3aa9ff" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityAddressAddressLine1_7e9da897-a93c-4f4d-a0cb-2c66fa3aa9ff" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_d50206ee-9a91-43bc-b75a-14227ac2ec6f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityAddressCityOrTown_d50206ee-9a91-43bc-b75a-14227ac2ec6f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_6a263e9a-0d58-4fdd-b9bb-6596824c18b0" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityAddressStateOrProvince_6a263e9a-0d58-4fdd-b9bb-6596824c18b0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_8683250f-5631-4a24-8a45-e7b377b52b1c" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityAddressPostalZipCode_8683250f-5631-4a24-8a45-e7b377b52b1c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_a6c6d0c1-4a4b-44ce-bb2b-ce7af4b68dc3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_CityAreaCode_a6c6d0c1-4a4b-44ce-bb2b-ce7af4b68dc3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_d96523fc-3546-43ba-8760-3f486a4854b7" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_LocalPhoneNumber_d96523fc-3546-43ba-8760-3f486a4854b7" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_348a3e8e-4b98-4391-b66b-d23ab5ae668b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_WrittenCommunications_348a3e8e-4b98-4391-b66b-d23ab5ae668b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_a6cc6807-fc91-4589-9e7c-f1d5fa1de233" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_SolicitingMaterial_a6cc6807-fc91-4589-9e7c-f1d5fa1de233" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_5ff8a521-0b74-4e5a-bf56-e9dbeebbf795" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_PreCommencementTenderOffer_5ff8a521-0b74-4e5a-bf56-e9dbeebbf795" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_f21ae0b5-28f1-4ded-a3f7-648f6c713486" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_f21ae0b5-28f1-4ded-a3f7-648f6c713486" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_021d5976-5469-438a-908a-a9135aecb634" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_Security12bTitle_021d5976-5469-438a-908a-a9135aecb634" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_673766ed-dd8d-4b29-9304-7721315e79db" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_TradingSymbol_673766ed-dd8d-4b29-9304-7721315e79db" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_680b78bd-b2b4-4bfe-a130-4f77ff5d4fbe" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_SecurityExchangeName_680b78bd-b2b4-4bfe-a130-4f77ff5d4fbe" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_072435ff-7986-471e-bde3-d312a81c7b25" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityEmergingGrowthCompany_072435ff-7986-471e-bde3-d312a81c7b25" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_02c0286b-be3b-4a3d-8fbf-5697609927de" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_AmendmentFlag_02c0286b-be3b-4a3d-8fbf-5697609927de" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_e526be3c-4078-4818-8f4f-6c6fc7d2ccf9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_bd1deec0-cb8d-41ed-a4c7-53300f3430a9" xlink:to="loc_dei_EntityCentralIndexKey_e526be3c-4078-4818-8f4f-6c6fc7d2ccf9" xlink:type="arc" order="21"/>
  </link:definitionLink>
</link:linkbase>
