Perhaps he will be best known for his play in the 1928-29 season when he posted 22 shutouts in just 44 games and an astounding goals against average of 0.92 for the season.

George began his stellar career in the Southwestern Ontario town of Berlin, which was known for its high percentage of people of German origin. Later, Berlin would become Kitchener. In his first season with the Berlin Union Jacks of the OHA in 1911-12, George posted a league leading 3 wins in 4 games. For the next 4 seasons he played with the Berlin City Seniors of the OHA Sr. League and in all 4 seasons he led the league in wins and in 2 of those seasons he led the league in Goals Against Average. For the 1916-17 season, Hainsworth played for Toronto Kew Beach in the City Sr. League and statistics for that year are not available.

In 1917-18, George began a six year stint with the Kitchener Greenshirts of the OHA Senior loop. While here, Hainsworth led the league twice in most wins, 3 times with the most shutouts and twice with the best Goals Against Average. On October 11, 1923 George signed as a free agent with the Saskatoon Crescents of the Western Canadian Hockey League. During his 3 seasons in Saskatoon he led the league each year in games played, twice with the most minutes played and once with the most shutouts.

Newsy Lalonde, a star in his own right with the Montreal Canadiens, had recommended that the Montreal management look at Hainsworth after the retirement and subsequent death of Georges Vezina during the 1925-26 season. It proved to be a good move on the part of the Canadiens as George immediately led the league in his rookie season in games played (44) and shutouts, (14). In 1926-27 he again led the league in games played, 44, and also in GAA, 1.05. The 1928-29 season was perhaps the pinnacle of George's career. Not only did he lead the league in games played, 44, but he also set a record that will be around for a great while longer…22 shutouts! Interestingly, George won 22 games that same season. It is no surprise that his GAA is also astonishingly low that season, 0.92, less than a goal a game! During his first 3 seasons with the Montreal Canadien's, Hainsworth won the Vezina Trophy each year. In 1929-30 rule changes brought about the forward pass and just as with other goaltenders of the era, Hainsworth's numbers began to fall in the shutout category, and his GAA began to creep up slowly.

George was a huge contributor to the back to back Stanley Cup that the Canadiens won in 1930 and 1931. In those two playoff seasons he led the league in games played, games won, minutes played, and shutouts. In the 1929-30 playoffs he also posted a league leading GAA of 0.75!

Despite these types of numbers, George was traded to the Toronto Maple Leafs for Lorne Chabot on October 1, 1933. Hainsworth kept up his winning ways while with the Leafs. During the four seasons he spent in Toronto he led the league every year in games played, twice in wins and in 3 playoff seasons he again led the league in all 3 seasons in games played, and in 1934-35 he led the playoffs with 2 shutouts in 7 games. Shortly after the beginning of the 1936-37 season, George was signed as a free agent by the Montreal Canadiens as Turk Broda took over the goaltending duties for the Leafs, where he played only 4 games with them.

During his career, Hainsworth was voted to the WHL All Star Team in 1926, won the Vezina Trophy 3 consecutive times in 1927, 1928 and 1929 and played in the NHL All Star Game in 1934. Hainsworth wasn't flashy and didn't put on a show for the fans. He simply stopped shots from the most dangerous players of his era, and did it day in day out better than anyone else. He still holds the record for the most shutouts in a single season with 22 and is second in all time shutouts with 94, and is second for the longest shutout streak. George still holds the Montreal Canadien team record for the most career shutouts (75), and the most shutouts in a season, (22). On October 9, 1950 George was killed in a car accident, and despite cries for his immediate admittance into the Hockey Hall of Fame, he was not honoured with his place among hockey's greatest players until 1961.