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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2025-07-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001878848</issuerCik>
        <issuerName>IREN Ltd</issuerName>
        <issuerTradingSymbol>IREN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001909120</rptOwnerCik>
            <rptOwnerName>Roberts Daniel John</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O IREN LIMITED</rptOwnerStreet1>
            <rptOwnerStreet2>LEVEL 6, 55 MARKET STREET</rptOwnerStreet2>
            <rptOwnerCity>SYDNEY</rptOwnerCity>
            <rptOwnerState>C3</rptOwnerState>
            <rptOwnerZipCode>2000</rptOwnerZipCode>
            <rptOwnerStateDescription>AUSTRALIA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Co-Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Ordinary Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13196304</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Awassi Capital Trust #2</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class B Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Awassi Capital Trust #2</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>75</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2033-08-18</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2400000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Awassi Capital Trust #2</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.29</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-12-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Awassi Capital Trust #2</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes ordinary shares (each, an &quot;Ordinary Share&quot;) of IREN Limited (the &quot;Company&quot;) and outstanding restricted stock units that will vest subject to the Reporting Person's satisfaction of applicable vesting conditions.</footnote>
        <footnote id="F2">Represents Ordinary Shares held through the Awassi Capital Trust #2, of which the Reporting Person has control over the trustee (the &quot;Awassi Trust&quot;). The Reporting Person disclaims beneficial ownership of the Ordinary Shares except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F3">Represents Class B Shares of the Company (each, a &quot;Class B Share&quot;) held through the Awassi Trust. The Reporting Person disclaims beneficial ownership of the Class B Shares except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F4">Represents an option to purchase Ordinary Shares (each, an &quot;Option&quot;). The Options vest in four tranches of 600,000 Ordinary Shares each, subject to the volume-weighted average price of an Ordinary Share equalling or exceeding specified vesting thresholds over any period of twenty (20) consecutive trading days. The initial vesting thresholds, determined as of the grant date and based on a fully diluted share count as of the grant date of 43,345,056 Ordinary Shares, were $370, $650, $925, and $1,850, respectively. These vesting thresholds are subject to adjustment in accordance with the terms of the Option, including adjustments to reflect any reorganization of the Company's capital structure and any issuance of actual or potential Ordinary Shares following the grant date.</footnote>
        <footnote id="F5">The Options are fully vested and exercisable.</footnote>
        <footnote id="F6">The Options are held through the Awassi Trust. The Reporting Person disclaims beneficial ownership of the Options except to the extent of his pecuniary interest therein.</footnote>
    </footnotes>

    <remarks>Exhibit List - Exhibit 24 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Cesilia Kim, as attorney-in-fact for Daniel Roberts</signatureName>
        <signatureDate>2025-07-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
