In commerce, a hypermarket (from the French hypermarché) is a store which combines a supermarket and a department store. The result is a gigantic retail facility which carries an enormous range of products under one roof, including full lines of fresh groceries and apparel. When they are planned, constructed, and executed correctly, a consumer can ideally satisfy all of their routine weekly shopping needs in one trip to the hypermarket.

The concept was pioneered by the French retail group Carrefour, which opened the first hypermarket in 1962 in Sainte-Geneviève-des-Bois near Paris. Carrefour is now the second-largest retail group in the world.

After the successes of super- and hyper-markets and amid fears that all smaller stores would be forced out of business, France enacted laws that made it more difficult to build hypermarkets and also restricted the amount of economic leverage that hypermarket chains can impose upon their suppliers (the Loi Galland). Large retailers for the most part work around the law by using loopholes. As of 2004, the Loi Galland has become increasingly controversial and there have been calls to amend it.

Other major hypermarket chains include:

• In the United States: Wal-Mart (known as Wal-Mart Supercenters), Fred Meyer (part of the Kroger group), Meijer, and SuperTargets. Stores in the United States tend to be single level enterprises with long operating hours; many of them, especially Wal-Marts, are continuously open except on major holidays (typically Thanksgiving and Christmas). Hypermarkets are very controversial in the U.S., with opposition coming primarily from preservationists who argue that they destroy conventional grocers, supermarkets, and downtowns. Hypermarkets have been most successful in northern states where adverse winter weather conditions make it inconvenient to visit multiple stores.
• In the United Kingdom, Tesco operates some hypermarkets (known as Tesco Extra stores). ASDA (owned by Wal-Mart) also operates some hypermarkets (ASDA WAL*MART Supercentres).
• In Spain, the largest hypermarkets are Eroski and Hipercor (short for Hipermercado El Corte Inglés). Carrefour also operates many stores in Spain. Spanish hypermarkets tend to be located in the industrial sprawl outside of Spain's dense urban cores.
• In Canada, Loblaws has developed many "superstore" locations across Ontario and Québec.

Another category of hypermarket is the membership based wholesale warehouse clubs that are popular in North America. Costco and Sam's Club, of which the latter is a division of Wal-Mart, are the largest companies in this category. However, it is debatable whether the warehouse clubs are true hypermarkets owing to their sparse interior decor and relatively limited range of products. To maximize turnover of inventory, they do not even attempt to carry a full range of products for each product type, but carry only those products likely to sell in bulk and in very high volume.

In California, another major hypermarket chain was the membership-based Fedco Superstores . In the mid-1990s, the hypermarket chain became defunct by the development of Wal-Mart and other discount retailers.