The outbound service from the London airport will operate on Wednesdays, Fridays and Sundays and the return service on Tuesdays, Thursdays and Saturdays.
Flights are operated with Boeing 787-9 Dreamliner aircraft, featuring 30 Air Canada signature class, 21 premium economy and 247 economy seats.
Air Canada now has a monopoly on Heathrow-Calgary services after British Airways axed the destination in March.
Air Canada currently offers daily nonstop services from Heathrow to Toronto and Vancouver, as well as a four-times weekly nonstop service between Heathrow and Montreal.
Stephen Gerrard, Air Canada general manager sales, U.K. and Ireland, said the move is an "important step forward" as the carrier rebuilds its international network.
"The restart of our service between Heathrow and Calgary provides our UK customers with even greater travel choice," he added.
