Asda Stores Ltd. is a British supermarket chain which retails food, clothing, general merchandise, toys and financial services. It also has a mobile telephone network, (via the Vodafone Network), Asda Mobile. Its head office is at Asda House in Leeds, West Yorkshire.

Asda became a subsidiary of the American retail giant Wal-Mart, the world’s largest retailer, in 1999, and is the UK's second largest chain by market share after Tesco. In December 2010, Asda's share of the UK grocery market stood at 16.5%.

Asda's marketing promotions are usually based solely on price, with Asda promoting itself under the slogan Britain's Lowest Priced Supermarket, 14 Years Running. As a wholly owned division of Wal-Mart, Asda is not required to declare quarterly or half-yearly earnings. It submits full accounts to Companies House each October.

Asda Stores Limited was founded as Associated Dairies & Farm Stores Limited in 1949 in Leeds. The adoption of the Asda name occurred in 1965 with the merger of the Asquith chain of three supermarkets and Associated Dairies; Asda is an abbreviation of Asquith and Dairies, often capitalised. For a short time in the 1980s Asda Stores Ltd was a subsidiary of Asda-MFI plc following a merger between the two companies. Other companies in the group were Associated Dairies Limited, the furniture retailer MFI and Allied Carpets. After the sale of MFI and Allied Carpets the company name changed to Asda Group plc. The dairy division was sold in a management buyout and renamed Associated Fresh Foods, meaning that Asda has since had no connection with one of the firms its name was derived from.