Worsley made his NHL debuts in 1952, playing for a miserable New York Rangers team. Even though New York finished last in the league, Gump was rewarded with the Calder Memorial Trophy. Despite this outstanding performance however, Worsley was shocked to learn the following season he was being sent to the Vancouver Canucks of the old Western Hockey League, the Rangers preferring Johnny Bower to him (meanwhile, Worsley had been named WHL's MVP and won the league championship with Vancouver). In 1954 however, Worsley was back in New York and would outplay Bower, earning the team's starter role for nearly a decade, often being the lone bright spot on an abysmal team - he would himself describe his stay in New York as "a jailhouse".
His involvement in a proposed players' union in the summer of 63 resulted in a quick trade to the Montreal Canadiens, where he played his best hockey and was a Stanley Cup winner in 1965, 1966, 1968 and 1969. He shared the Vezina Trophy with Charlie Hodge in 1966; he repeated the feat in 1968, this time sharing it with Rogatien Vachon.
A nervous breakdown suffered in 1969 due to his fear of flights nearly put an end to his career. However, the Minnesota North Stars took their chance and picked up Worsley's rights. They successfully brought him back to the game by assuring him that the Central Division North Stars had much less travel to do than other teams and it paid off. The duo Worsley-Maniago starred for the young North Stars until Gump retired at the age of 44 in in 1974.