Munn was a prop-forward who played with St. George immediately after World War II. After his discharge from the AIF,[2] Jack Munn joined St George and played five seasons between 1946-1949 and 1951.[3]
He moved the Queensland in 1950, and represented Queensland against New South Wales in that year before returning to St George. Munn scored a try in the club's 1946 Grand final loss to Balmain.
He won a premiership with St. George when he played prop in the 1949 Grand Final.[4] In 1950, Munn accepted a captain coach role for Ingham, Queensland and consequentially played representative football for Queensland. in 1950 and only a bad injury stopped him from playing for the Kangaroos.[5][6]