<SEC-DOCUMENT>0001973239-26-000056.txt : 20260416
<SEC-HEADER>0001973239-26-000056.hdr.sgml : 20260416
<ACCEPTANCE-DATETIME>20260416165956
ACCESSION NUMBER:		0001973239-26-000056
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260414
FILED AS OF DATE:		20260416
DATE AS OF CHANGE:		20260416

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Haas Rene A.
		CENTRAL INDEX KEY:			0001998912
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-41800
		FILM NUMBER:		26868336

	MAIL ADDRESS:	
		STREET 1:		120 ROSE ORCHARD WAY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95134

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARM HOLDINGS PLC /UK
		CENTRAL INDEX KEY:			0001973239
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		ORGANIZATION NAME:           	04 Manufacturing
		EIN:				000000000
		STATE OF INCORPORATION:			X0
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		110 FULBOURN ROAD
		CITY:			CAMBRIDGE
		STATE:			X0
		ZIP:			CB1 9NJ
		BUSINESS PHONE:		44 1223 400 400

	MAIL ADDRESS:	
		STREET 1:		110 FULBOURN ROAD
		CITY:			CAMBRIDGE
		STATE:			X0
		ZIP:			CB1 9NJ

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Arm Holdings Ltd
		DATE OF NAME CHANGE:	20230411
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1776373191.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-04-14</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001973239</issuerCik>
        <issuerName>ARM HOLDINGS PLC /UK</issuerName>
        <issuerTradingSymbol>ARM</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001998912</rptOwnerCik>
            <rptOwnerName>Haas Rene A.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O ARM HOLDINGS PLC</rptOwnerStreet1>
            <rptOwnerStreet2>110 FULBOURN ROAD</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>X0</rptOwnerCountry>
            <rptOwnerZipCode>CB1 9NJ</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>1</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Ordinary Shares</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2026-04-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5646</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>160.57</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>277333</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Ordinary Shares</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2026-04-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3483</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>161.21</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>273850</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Ordinary Shares</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2026-04-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>170</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>163</value>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>273680</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Ordinary shares, nominal value 0.001 GBP per share (&quot;Ordinary Shares&quot;), are held in the form of American Depositary Shares (&quot;ADSs&quot;). Each ADS represents 1 Ordinary Share.</footnote>
        <footnote id="F2">The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on June 11, 2025.</footnote>
        <footnote id="F3">Represents weighted average sales price. The shares were sold at prices ranging from $160.00 to $160.96. The reporting person will provide upon request, to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F4">Represents weighted average sales price. The shares were sold at prices ranging from $161.00 to $161.91. The reporting person will provide upon request, to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F5">Represents weighted average sales price. The shares were sold at prices ranging from $162.99 to $163.01. The reporting person will provide upon request, to the SEC, the Issuer or security holder of the Issuer, full information regarding the number of shares sold at each separate price.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ George Kanelos, as Attorney-in-Fact for Rene A. Haas</signatureName>
        <signatureDate>2026-04-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
