Cheevers' professional hockey career began in 1956 at the age of 16 when he played for the St. Michael's Majors of the Ontario Hockey Association . He was owned by the Toronto Maple Leafs until the Boston Bruins drafted him in 1965. He spent six years in all in the minors until, by 1967 , he was the team's number one goalie. He was a member of both the 1970 and 1972 Stanley Cup winning teams, gaining a reputation as a driven, "money" goaltender.
Cheevers' unusual stitch-pattern goaltender mask came after he had been struck on it by a puck hard enough to have caused him injury if he had not been wearing one, and he had the team trainer paint on the mask the stitches he would have otherwise received. Ever after, any time he was similarly struck, he would have a new stitch-mark painted on. The mask became one of the most recognized of the era, and is now in the Hockey Hall of Fame.
His cumulative NHL goals against average was 2.89. He recorded 230 NHL wins, played in 419 NHL games, and recorded 26 NHL shutouts. He was also second in the WHA's history in career GAA and shutouts, despite playing in only half the league's seasons.