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

    <schemaVersion>X0205</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2012-04-18</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001273801</issuerCik>
        <issuerName>NORTHSTAR REALTY FINANCE CORP.</issuerName>
        <issuerTradingSymbol>NRF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001541849</rptOwnerCik>
            <rptOwnerName>Lieberman Ronald J.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NORTHSTAR REALTY FINANCE CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>399 PARK AVENUE, 18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP &amp; General Counsel</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>LTIP Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>143129</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>LTIP Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>27881</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents units of limited partnership interest structured as profits interests in NorthStar Realty Finance Limited Partnership (&quot;NRFLP&quot;), a majority-owned subsidiary and the operating partnership of NorthStar Realty Finance Corp. (the &quot;Company&quot;). Conditioned on minimum allocations to the capital accounts of the LTIP Unit for federal income tax purposes, each LTIP Unit may be converted, at the election of the holder, into one common unit of limited partnership interest in NRFLP. Each of the OP Units underlying these LTIP Units are redeemable at the election of the OP Unit holder for (1) cash equal to the then fair market value of one (1) share of Common Stock or (2) at the option of the Company in its capacity as general partner of NRFLP, one (1) share of common stock, par value $0.01 per share of the Company (&quot;Common Stock&quot;). The rights to convert LTIP Units into OP Units and redeem OP Units do not have expiration dates.</footnote>
        <footnote id="F2">These LTIP Units were granted as an inducement for Mr. Lieberman to accept employment with the Company. These LTIP Units vest as to 1/12 of the LTIP Units on the 29th day of January, April, July and October, commencing on July 29, 2011.</footnote>
        <footnote id="F3">These LTIP Units were granted as long-term performance based incentive compensation for 2011. These LTIP Units vest as to 1/12 of the LTIP Units on the 29th day of January, April, July and October, commencing on April 29, 2012.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Ronald J. Lieberman</signatureName>
        <signatureDate>2012-04-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
