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 with the Quarterly Report of Costco Wholesale Corporation (the Company) on Form 10-Q for the quarter ended February 12, 2023, as filed with the Securities and Exchange Commission (the Report), I, W. Craig Jelinek, Chief Executive Officer and Director of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) 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.

/s/ W. CRAIG JELINEK	Date: March 8, 2023
W. Craig Jelinek
Chief Executive Officer and Director

A signed original of this written statement has been provided to and will be retained by Costco Wholesale Corporation and furnished to the Securities and Exchange Commission or its staff upon request.

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Costco Wholesale Corporation (the Company) on Form 10-Q for the quarter ended February 12, 2023, as filed with the Securities and Exchange Commission (the Report), I, Richard A. Galanti, Executive Vice President, Chief Financial Officer and Director of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) 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.

/s/ RICHARD A. GALANTI	Date: March 8, 2023
Richard A. Galanti
Executive Vice President, Chief Financial Officer and Director

A signed original of this written statement has been provided to and will be retained by Costco Wholesale Corporation and furnished to the Securities and Exchange Commission or its staff upon request.