a321iren-2025x0930xex321

Exhibit 32.1 CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER PURSUANT TO 18 U.S.C. SECTION 1350 AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 Pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, I, Daniel Roberts, the Co-Chief Executive Officer of IREN Limited (the “Company”), hereby certify, that, to my knowledge: 1. The Quarterly Report on Form 10-Q for the period ended September 30, 2025 (the “Report”) of the Company fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934; and 2. The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. Date: November 6, 2025 /s/ Daniel Roberts Name: Daniel Roberts Title: Co-Chief Executive Officer