He played for the St Michaels College Majors from 1958 to 1961, winning the Memorial Cup in 1961. O'Malley was a member of the Canada national men's ice hockey team from 1964 to 1969. He won bronze medals at the World Championships in 1965, 1966, and 1967. He also won a bronze medal in the 1968 Olympics. He was the coach of the University of British Columbia in 1986-87. He spent 23 years at Athol Murray College of Notre Dame as a coach, teacher and evetnually president of the school from 2003 to 2006. He was inducted into the Saskatchewan Hockey Hall of Fame in 2016 in the builders category.