Cheevers' unusual stitch-pattern goaltender mask came after a puck hit him in the face during practice. Cheevers, never one to miss an opportunity to skip out of practice, went to the dressing room. Bruins coach Harry Sinden followed him to the dressing room, where he found Cheevers enjoying a beer and smoking a cigarette. Sinden told Cheevers, who wasn't injured, to get back on the ice. In jest, John Forestall, the team trainer, painted a stitch mark on his mask. 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 the original mask is now on the wall of his grandson's bedroom. Another version is on display in the Hockey Hall of Fame.

In the fall of 1972, he jumped to the fledgling World Hockey Association, playing three and a half seasons for the Cleveland Crusaders as one of the league's best goalies, winning First Team All-Star honors in 1973 and Second Team honors in 1974 and 1975.

Returning to the Bruins during the 1976 season after financial disputes with Cleveland management, Cheevers finished out his playing career at the end of the 1980 season. After hanging up his pads, he became the Bruins' coach, a position he held for four and a half seasons.

His cumulative NHL goals against average was 2.89. He recorded 230 NHL wins, played in 418 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. In 1971-72, he set a record, going undefeated in 33 consecutive games.