James Gaye Stewart, born in Fort William, Ontario, in June 1923, began his hockey journey at 16 years old. He played for the Port Arthur Bruins of the Thunder Bay Junior A Hockey League. Over the next two seasons, Stewart moved up the ranks of Ontario hockey, playing in the Ontario Hockey Association and the American Hockey League, before his NHL debut.

His first experience in the NHL wasn't during the regular season. He was called up by the Toronto Maple Leafs in 1942 during the Stanley Cup Final, helping the team win the championship. His regular season debut came the following season, on his way to a Calder Trophy-winning performance in 1942-43 for the Maple Leafs, a season that wouldn't soon be forgotten.

On October 31, 1942, Stewart made his NHL regular season debut, in a 7-2 win over the New York Rangers, where he scored two goals and an assist. Following this start, he had 22 penalty minutes, before a streak of five consecutive games with goals, scoring six goals in that period.

In his rookie season, Stewart contributed 24 goals and 47 points in 48 games, proving his worth to the team. He added two more points in four playoff games, although the Maple Leafs did not advance past the Detroit Red Wings in the first round.

After winning the Stanley Cup the previous season with only one NHL game under his belt, Stewart became the first player in NHL history to win the Cup before winning the Calder Trophy as the league's rookie of the year.

His almost point-per-game season earned him the award for best rookie, surpassing Montreal's Glen Harmon and Maurice 'The Rocket' Richard in the Calder voting, despite Richard's injuries. Stewart's victory was the start of a distinguished career.

Stewart's rookie season also saw him voted second in Hart Trophy voting and third in Lady Byng. Throughout his career, Stewart played 502 regular season games, accumulating 185 goals and 344 points in nine seasons with the Maple Leafs, Chicago Black Hawks, New York Rangers, Detroit Red Wings, and Montreal Canadiens.

Despite his outstanding season and over 500 games played, Stewart was never inducted into the Hockey Hall of Fame. He was recognized as one of the top 100 Maple Leafs of all time, at number 67, and was inducted into the Northwestern Ontario Sports Hall of Fame in 1983.

During his career, Stewart played in five postseasons, adding two goals and 11 points in 27 games with the Maple Leafs, Red Wings, and Canadiens. In addition to the Stanley Cup in 1941-42, Stewart was also part of the Cup-winning Maple Leafs in 1946-47.

In nine seasons, Stewart reached the 20-goal mark six times, including a career-high 37 goals at age 22, following a two-year hiatus in World War II. Upon his return, his 37 goals led the NHL in 1945-46 and, until Auston Matthews led the NHL in goals in 2020-21, it was the last time a Maple Leafs player led the league.