Loblaw Companies Limited is a Canadian retailer encompassing corporate and franchise supermarkets operating under 22 regional and market-segment banners (including Loblaws), as well as pharmacies, banking and apparel. Loblaw operates a private label program that includes grocery and household items, clothing, baby products, pharmaceuticals, cellular phones, general merchandise and financial services. Loblaw is the largest Canadian food retailer, and its brands include President's Choice, No Name and Joe Fresh. It is controlled by George Weston Limited, a holding company controlled by the Weston family; Galen G. Weston is the chair of the Loblaw board of directors, as well as chair of the board of directors and CEO of Canada-based holding company George Weston.

Most of Loblaw's 220,000 full-time and part-time employees are members of the United Food and Commercial Workers, with the exception of workers at The Real Canadian Wholesale Club in Alberta, who are members of the Christian Labour Association of Canada.^{[citation needed]}

Loblaw's regional food distribution divisions include Westfair Foods Ltd. in Western Canada and Northern Ontario, National Grocers Co. Ltd. in Ontario, Provigo Inc. in Quebec, and Atlantic Wholesalers Ltd. in Atlantic Canada.

In 1919, Toronto grocers Theodore Pringle Loblaw and J. Milton Cork opened the first Loblaw Groceterias store modelled on a new and radically different retail concept, namely "self serve". The traditional grocery store provided a high level of personal service but was a labour-intensive operation. Customers typically had to wait while a clerk fetched items from behind a counter. Other goods, such as sugar and flour, had to be individually weighed and the order was then tallied by hand and added to the customer’s account. Home delivery, by wagon, was usually included free of charge. Loblaw and Cork, friends from the days when both worked as young clerks in the Cork family grocery store, believed they could cut costs by introducing self service combined with cash and carry. While cash stores were not new, the idea of allowing customers to select their own merchandise was a new concept. The pair had heard of the Piggly Wiggly "self-serving store" in the United States and travelled to Memphis, Tennessee, to see it in operation first hand. With customers allowed to browse freely, pick up their own goods and then pay cash at a central checkout counter, with no credit or home delivery, operating costs were reduced. The two came away convinced that a similar style of operation could work in Canada. But Loblaw was met with scepticism:

In the early days when I started the cash and carry business, I was told that it could not be done, but my contention was that the people of Toronto and Ontario would welcome the opportunity to carry their groceries home, providing I could offer them higher qualities at a much lower price than they were used to paying.

The first Loblaw Groceterias Co. store opened at 2923 Dundas St. W., Toronto, in June 1919. Months later, a second location, at 528 College Street, followed. The ’groceterias’ name was apparently derived from cafeteria – a popular self serve restaurant format. Along with the Loblaw name, the outlets featured big "We Sell For Less" signs across their storefronts. Inside, the stores were clean and well lit, with items neatly displayed and clearly marked:

From the entry, one passes through a turnstile which permits egress only. Just inside are piles of market baskets from which the customer helps himself and proceeds in his quest for food at lower prices. Out in front, the shelves are packed with bottled and canned goods, whose names are household words, all plainly tagged with price. Further back, one finds teas, coffee fancy biscuits and cheese, all wrapped ready to carry home .... The customer having selected her purchases, carries her basket to one of the counters near the point of exit. Here her purchases are quickly totaled on an adding machine and she receives her slip. While she pays the bill her groceries are neatly packed in a larger bag.."

While produce was limited and fresh meats largely excluded from the early stores, sales proved strong. Within its first five months of operation, the chain's second location had expanded its sales room into that part of the store normally reserved for storage. In spite of the success of the new groceteria format, Cork did not feel that traditional, full-service grocery stores were in danger of going out of business since many customers still valued the extension of credit, individual serve and home delivery. A year later, another Toronto grocer, C.B. Shields, joined with Loblaw and Cork.