The 1921 MAFA season was the 26th season of the Metropolitan Amateur Football Association (MAFA), an Australian rules football competition played in the state of Victoria. The season began on 7 May and concluded on 3 September, comprising a 13-match home-and-away season, followed by a two-week finals series.
won the MAFA premiership for the first time, defeating by five points in the 1921 MAFA Grand Final.
Six new teams entered the MAFA in 1921 â Hampton, Old Brightonians, Old Scotch Collegians, Old Trinity, Sandringham and .
joined the MAFA after leaving the Victorian Junior Football League (VJFL). They joined the University Football Club's other team, , which had crossed from the VJFL in 1920. The teams were known as the "Blues" and the "Blacks" respectively, although the nicknames were not formally used until 1930.