The 1931 WANFL season was the 47th season of the Western Australian National Football League and the first under that moniker, having been called the West Australian Football League (WAFL) until 1930. The season saw East Fremantle win its fourth consecutive premiership for the second time, having already done so between 1908 and 1911. It also saw a major revival by East Perth, who had fallen to a clear last in 1929. The Great Depression and consequent search for work saw the beginning of the first major drain of Western Australian players to powerful VFL clubs, with the loss of George Moloney to Geelong, Ron Cooper to Carlton and Keith Hough to South Melbourne, where Hough never played a single match due to the WANFL's refusal to grant the VFL Swans a clearance.