McCormack began his National Hockey League career with the Toronto Maple Leafs in 1947. He would also play for the Montreal Canadiens and Chicago Black Hawks. He would retire from the NHL after the 1955 season. McCormack won two Stanley Cups in his career, one in 1951 with Toronto and another in 1953 with Montreal. He also won the 1945 Memorial Cup with the St. Michael's Majors and the Allan Cup in 1950 with the senior Toronto Marlboros.