Born in Fort William, Ontario, Stewart was promoted from the minors in 1942 to play in one game of the Stanley Cup Finals, where he helped the Toronto Maple Leafs win the championship. The next season, Stewart won the 1943 Calder Trophy, beating out Maurice 'The Rocket' Richard of the Montreal Canadiens. He became the first player to win the Stanley Cup before the Calder. Danny Grant, Tony Esposito and Ken Dryden have accomplished it as well since then.