Exhibit 32.1

SECTION 1350 CERTIFICATIONS

I, Kevin R. Mandia, certify to the best of my knowledge, pursuant to 18 U.S.C. Section 1350, that the Annual Report of Mandiant, Inc. on Form 10-K for the fiscal year ended December 31, 2021 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Form 10-K fairly presents, in all material respects, the financial condition and results of operations of Mandiant, Inc.

Date: March 1, 2022	/s/ Kevin R. Mandia
	Kevin R. Mandia
	Chief Executive Officer
	(Principal Executive Officer)

I, Frank E. Verdecanna, certify to the best of my knowledge, pursuant to 18 U.S.C. Section 1350, that the Annual Report of Mandiant, Inc. on Form 10-K for the fiscal year ended December 31, 2021 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that information contained in such Form 10-K fairly presents, in all material respects, the financial condition and results of operations of Mandiant, Inc.

Date: March 1, 2022	/s/ Frank E. Verdecanna
	Frank E. Verdecanna
	Executive Vice President and Chief Financial Officer
	(Principal Financial Officer)