At age four, Sam Steinberg's family immigrated to Canada, settling in Montreal where his mother opened a small grocery store. In 1934, Sam Steinberg opened his first self-service grocery supermarket in the city. By the end of the 1950s his stores were a dominant force throughout the Province of Quebec and in 1959 expanded into the Province of Ontario with the acquisition of 38 Grand Union stores.

Sam Steinberg married his cousin Helen Roth (daughter of his mother Ida's brother, Lewis) in 1929. Children - Marilyn, Rita (died in 1970), Evelyn (died 1993) and Mitzi.

Helen Steinberg died in 2007 at the age of 98, and was buried next to her husband in Montreal's Shaar Hashomayim cemetery.