Exhibit 99.1

News from

COSTCO WHOLESALE CORPORATION REPORTS FIRST QUARTER FISCAL

YEAR 2013 OPERATING RESULTS

ISSAQUAH, Wash., December 12, 2012—Costco Wholesale Corporation (“Costco” or the “Company”) (Nasdaq: COST) announced today its operating results for the first quarter (twelve weeks) of fiscal 2013, ended November 25, 2012.

Net sales for the quarter increased ten percent, to $23.20 billion from $21.18 billion during the first quarter last year. Comparable sales for the first quarter of fiscal 2013 were as follows:

Inflation in gasoline prices and strengthening foreign currencies had a positive impact on comparable sales. Excluding these effects, comparable sales were as follows:

Net income for the quarter was $416 million, or $.95 per diluted share, compared to $320 million, or $.73 per diluted share, last year. Last year’s net income was negatively impacted by a $12 million charge (or $.03 per diluted share) related to settlement of an income tax audit of the Company’s Mexico operation, and a $17 million charge (or $.04 per diluted share) related to contributions to an initiative reforming alcoholic beverage laws in Washington State.

Costco currently operates 621 warehouses, including 448 in the United States and Puerto Rico, 85 in Canada, 32 in Mexico, 23 in the United Kingdom, 13 in Japan, nine in Taiwan, eight in Korea, and three in Australia. The Company plans to open one additional new warehouse (Gwangmyeong, Korea) before the end of calendar year 2012. The Company also operates Costco Online, electronic commerce web sites, at www.costco.com (U.S.), www.costco.ca (CN), and www.costco.co.uk (United Kingdom).

1

A conference call to discuss these fiscal 2013 first quarter operating results is scheduled for 7:00 a.m. (PT) today, December 12, 2012, and is available via a webcast on www.costco.com (click on Investor Relations and “Play webcast”).

Certain statements contained in this document constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. For these purposes, forward-looking statements are statements that address activities, events, conditions or developments that the Company expects or anticipates may occur in the future. Such forward-looking statements involve risks and uncertainties that may cause actual events, results or performance to differ materially from those indicated by such statements. These risks and uncertainties include, but are not limited to, domestic and international economic conditions, including exchange rates, the effects of competition and regulation, uncertainties in the financial markets, consumer and small business spending patterns and debt levels, conditions affecting the acquisition, development, ownership or use of real estate, actions of vendors, rising costs associated with employees (including health care costs), energy, and certain commodities, geopolitical conditions and other risks identified from time to time in the Company’s public statements and reports filed with the Securities and Exchange Commission.

2

COSTCO WHOLESALE CORPORATION

CONSOLIDATED STATEMENTS OF INCOME

(dollars in millions, except per share data)

(unaudited)

3

COSTCO WHOLESALE CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS

(dollars in millions)

(unaudited)

Subject to Reclassifications

4