<SEC-DOCUMENT>0000315213-22-000026.txt : 20220324
<SEC-HEADER>0000315213-22-000026.hdr.sgml : 20220324
<ACCEPTANCE-DATETIME>20220324172607
ACCESSION NUMBER:		0000315213-22-000026
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20220323
FILED AS OF DATE:		20220324
DATE AS OF CHANGE:		20220324

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MESSMER HAROLD M JR
		CENTRAL INDEX KEY:			0001183491

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10427
		FILM NUMBER:		22767583

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_164815714869803.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2022-03-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183491</rptOwnerCik>
            <rptOwnerName>MESSMER HAROLD M JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2884 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Chairman</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2022-03-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>68692</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>673569</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2022-03-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>9890</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>683459</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2022-03-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value>E</value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>220484</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By GRATs</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents additional shares issued as a result of the certification of a performance condition for the performance shares granted on April 15, 2019, which will vest on April 15, 2022.</footnote>
        <footnote id="F2">Granted pursuant to the Stock Incentive Plan.</footnote>
        <footnote id="F3">Reflects a distribution by existing GRATs of 112,520 shares to the Reporting Person on March 14,2022. All of such GRATs were for the benefit of relatives of the Reporting Person and the Reporting Person served as a Trustee. As a result of such distribution, the distributed shares that were previously reported as indirectly held are now reported as directly held.</footnote>
        <footnote id="F4">Reflects a distribution by existing GRATs of shares to the Reporting Person's family members in March 2022. As a result of such distribution, certain shares that were previously reported as indirectly have been transferred to beneficiaries of the GRATs and the GRATs no longer hold any shares.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Harold M. Messmer, Jr.</signatureName>
        <signatureDate>2022-03-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
