Starting out as a  in the lower grades at the Mascot Juniors RLFC, Treweek was moved into the second-row upon reaching first grade and won five premierships with South Sydney, captaining the side in the 1931 and 1932 premiership victories.
Treweek started his career as a player in the lower grades at the Mascot Juniors RLFC. He progressed to the second-row and achieved multiple premierships with South Sydney, leading the team in the 1931 and 1932 premiership victories.