The 1940 New South Wales Rugby Football League premiership was the 33rd season of Sydney's top-level rugby league football club competition, Australia's first. Eight teams from across the city contested the premiership during the season, which lasted from April until August, culminating in Eastern Suburbs' victory over Canterbury-Bankstown in the final.
For this season St. George returned to Hurstville Oval as their home ground.
In the two semi finals, minor premiers Eastern Suburbs defeated St. George whilst fourth-placed Canterbury-Bankstown beat second-placed Newtown. Eastern Suburbs then beat Canterbury-Bankstown in the Final to collect their eighth premiership.