<SEC-DOCUMENT>0000315213-20-000035.txt : 20200331
<SEC-HEADER>0000315213-20-000035.hdr.sgml : 20200331
<ACCEPTANCE-DATETIME>20200331171517
ACCESSION NUMBER:		0000315213-20-000035
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20200330
FILED AS OF DATE:		20200331
DATE AS OF CHANGE:		20200331

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BUCKLEY MICHAEL C
		CENTRAL INDEX KEY:			0001280300

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10427
		FILM NUMBER:		20762769

	MAIL ADDRESS:	
		STREET 1:		C/O ROBERT HALF INTERNATIONAL INC
		STREET 2:		5720 STONERIDGE DR STE 3
		CITY:			PLEASANTON
		STATE:			CA
		ZIP:			94588

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ROBERT HALF INTERNATIONAL INC.
		CENTRAL INDEX KEY:			0000315213
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-HELP SUPPLY SERVICES [7363]
		IRS NUMBER:				941648752
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2884 SAND HILL RD
		STREET 2:		STE 200
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025
		BUSINESS PHONE:		6502346000

	MAIL ADDRESS:	
		STREET 1:		2884 SAND HILL ROAD
		STREET 2:		STE 200
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HALF ROBERT INTERNATIONAL INC /DE/
		DATE OF NAME CHANGE:	19920703

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BOOTHE FINANCIAL CORP /DE/
		DATE OF NAME CHANGE:	19870721

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BOOTHE INTERIM CORP
		DATE OF NAME CHANGE:	19600201
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_158568929818796.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-03-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000315213</issuerCik>
        <issuerName>ROBERT HALF INTERNATIONAL INC.</issuerName>
        <issuerTradingSymbol>RHI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001280300</rptOwnerCik>
            <rptOwnerName>BUCKLEY MICHAEL C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2613 CAMINO RAMON</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN RAMON</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94583</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice President &amp; CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-03-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5102</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>180530</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-03-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>14269</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.31</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>166261</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents additional shares granted as a result of the certification of a performance condition for performance shares which were both granted and vest on March 30, 2020.</footnote>
        <footnote id="F2">Granted pursuant to the Stock Incentive Plan.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Michael C. Buckley</signatureName>
        <signatureDate>2020-03-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
