He played junior hockey for the Regina Abbotts in 1939-40 and senior for the Regina Rangers in 1940-41, winning the Allan Cup that year. Mario played 9 games for the Boston Bruins in 1941-42 and also played for the Hershey Bears. He then played for the senior Cornwall Army team in 1942-43 and joined the Canadian military for 1943-44. Returning to hockey in 1944-45, he played a full season for the Bruins. Mario then played seven seasons for the Hershey Bears and one (1952–53) for the Quebec Aces. He retired in 1953. In the NHL he played in 53 games and scored 9 goals and 19 assists.