<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-12-01</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001799191</issuerCik>
        <issuerName>Oncology Institute, Inc.</issuerName>
        <issuerTradingSymbol>TOI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001945281</rptOwnerCik>
            <rptOwnerName>Ling Gabriel</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE ONCOLOGY INSTITUTE OF HOPE</rptOwnerStreet1>
            <rptOwnerStreet2>18000 STUDEBAKER ROAD, SUITE 800</rptOwnerStreet2>
            <rptOwnerCity>CERRITOS</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90703</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <ownerSignature>
        <signatureName>/s/ Mark Hueppelsheuser, Attorney-in-Fact for Gabriel Ling</signatureName>
        <signatureDate>2025-12-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
