Long before he played his first NHL game in 1926, Hainsworth established himself as one of the top goalies of his era.

The Toronto native moved with his family when he was a kid to Berlin (now Kitchener), where he began forging a reputation as one of the top amateur goalies in hockey with the Berlin Seniors of the Ontario Hockey Association. From 1912-16, he led the league in victories in four consecutive seasons and helped Berlin win the OHA title in 1913-14.

In 1917, Hainsworth started a six-year run with the Kitchener Greenshirts (OHA) by helping them win the Allan Cup (national senior amateur men's ice hockey champions of Canada) in his first season. One of his other highlights with the Greenshirts came during the 1923 OHA playoffs when a game he played against the Toronto Argonaut Rowing Club was the first broadcast of Hockey Hall of Fame announcer Foster Hewitt.

When Saskatoon of the Western Canada Hockey League needed a goalie heading into the 1923-24 season, it signed Hainsworth to his first professional contract. He was a workhorse for Saskatoon and led the WCHL in minutes played in each of his three seasons with the Crescents.

The Montreal Canadiens signed to Hainsworth on Aug. 23, 1926 to succeed George Vezina, who died March 27 of that year from tuberculosis. The team created the Vezina Trophy, awarded to the top goalie in the NHL, in his honor and Hainsworth won it in the first three seasons of its existence (1927-29).

In 1928-29, Hainsworth had one of the most remarkable seasons by a goalie in NHL history with records for shutouts (22) and goals-against average (0.92) that stand to this day. He allowed 43 goals in 44 games and went 22-7-15.

He set another NHL record in 1930 that still endures, going 270:08 without allowing a goal during the Stanley Cup Playoffs. His spectacular run played a huge role in helping the Canadiens win their first of two consecutive Stanley Cup championships.

Hainsworth was traded to the Toronto Maple Leafs for goalie Lorne Chabot on Oct. 1, 1933 and helped Toronto reach the 1935 Stanley Cup Final, where they were swept in three games by the Montreal Maroons. The following season he was released by Maple Leafs owner Conn Smythe, who wanted to give young Turk Broda a shot.

Hainsworth subsequently signed with the Canadiens and played four games for Montreal. He played his final NHL game Dec. 20, 1936 and officially retired shortly afterward. He was inducted into the Hockey Hall of Fame in 1961 with some impressive stats including 94 shutouts, the most in NHL history at that time. He was elected to the Ontario Sports Hall of Fame in 2004.