Exhibit 21.1

SUBSIDIARIES OF THE COMPANY

The following is a list of subsidiaries of the Company as of August 31, 2025, omitting subsidiaries which, considered in the aggregate, would not constitute a significant subsidiary.

Subsidiaries

State or Other Jurisdiction of Incorporation or Organization

Name under Which Subsidiary Does Business

Costco Wholesale Membership, Inc.

California

Costco Wholesale Membership, Inc.

Costco Wholesale Canada Ltd.

Canadian Federal

Costco Wholesale Canada, Ltd.

NW Re Limited

Arizona

NW Re Limited

Costco Insurance Agency, Inc.

Washington

Costco Insurance Agency, Inc.

Price Costco International, Inc.

Nevada

Price Costco International, Inc.

Costco Wholesale Korea, Ltd.

Korea

Costco Wholesale Korea, Ltd.

Costco Wholesale Japan, Ltd.

Japan

Costco Wholesale Japan, Ltd.

Costco de Mexico, S.A. de C.V.

Mexico

Costco de Mexico, S.A. de C.V.

Costco Wholesale UK Limited

United Kingdom

Costco Wholesale UK Limited

Costco Wholesale Taiwan, Inc.

Taiwan

Costco Wholesale Taiwan, Inc.

Costco Wholesale Australia, Pty. Ltd.

Australia

Costco Wholesale Australia, Pty. Ltd.