Coming straight from high school, Knowles played for his hometown Sarnia Imperials from 1946 to 1950, with his finest season being 1949, when he was an all-star and won the Imperial Oil Trophy as OFRU most valuable player. He later played two seasons with the Winnipeg Blue Bombers,[3] returned to Sarnia for a season, and finished his football career playing a game for the 1954 inaugural BC Lions team.[4]
In 1990 he was elected to the Sarnia Lambton Sports Hall of Fame.[5] He died in 2017.[6]