Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection betfred gameswith the Quarterly Report of Cleveland-Cliffs Inc. (the “Company”) on Form 10-Q for the period ended March 31, 2024, as filed with the Securities and Exchange Commission on Betfredthe date hereof (the “Form 10-Q”), I, Lourenco Goncalves, Chairman, President and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. betfred sportsbookSection 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to such officer’s knowledge:

(1)The Form 10-Q fully betfred sportsbookcomplies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and

(2)The information contained in the Form 10-Q fairly presents, betfred sportsbook reviewin all material respects, the financial condition and results of operations of the Company as of the dates and for the periods expressed in the Form 10-Q.

Date:						April 25, 2024
						By:			/s/ Lourenco Goncalves
									Lourenco Goncalves
									Chairman, President and Chief Executive Officer