Mr. Sub was founded in Toronto, Canada, in 1968 by two friends, Jack Levinson, an accounting clerk, and Earl Linzon, a gym teacher,[6] with $1500 start-up capital (equivalent to $13,000 in 2023).

[4] Mr. Sub was originally the only major franchise retailer of submarine sandwiches in Canada, until going into decline in the mid-1990s after the arrival of American chains such as Subway and Quiznos, facing stiff competition from those chains, notably surviving on its dominance of the small town and countryside markets, and regular take-out food courts of public institutions i.e. hospitals, courthouses, civil, law and financial offices and low-key shopping complexes that cater to an older demographic.

[7] On August 18, 2011, MTY Food Group, which by then owned Country Style, announced that it would acquire Mr. Sub at the end of October 2011 for $23 million.

[8] Mr. Sub's main product is the submarine sandwich (or "sub"); a long roll, similar to a baguette, filled with meat, cheese, sauces, and vegetables.

Some of the marketing methods that Mr. Sub has adapted into its operations include: strategic partnerships with the country's most visible sports franchises, national promotions, and ongoing in-restaurant campaigns.

[11] The following slogans, in chronological order, have been used by Mr. Sub: "Lub my Sub"; "Fresh thinking is what we are"; "Taste a Canadian Tradition"; "It's not a sandwich it's a Sub"; "There's always something good going down at Mr. Sub"; and "Oh Canada, Oh Mr. Sub"[citation needed].