He played for the Montreal Canadiens, New York Islanders, Chicago Black Hawks, and Kansas City Scouts. An original Islander, Gagnon recorded three points, including the winning goal, in the Islanders first win on October 12, 1972.
Gagnon's hockey career spanned multiple teams: Montreal Canadiens, New York Islanders, Chicago Black Hawks, and Kansas City Scouts. As one of the Islanders' founding members, Gagnon scored three points, including the game-winning goal, in their first win on October 12, 1972.