Growing up in Pingelly in the Wheatbelt region of Western Australia, Winmar began his career with South Fremantle, playing 58 games at the club before being recruited prior to the 1987 season by St Kilda. In a twelve-season career with St Kilda, Winmar won the club's best and fairest award, the Trevor Barker Award, in 1989 and 1995 and was also twice named in the All-Australian team. He left St Kilda at the end of the 1998 season and was drafted by the Western Bulldogs, playing one further season in the AFL before retiring at the end of the 1999 season. Having represented Western Australia in eight interstate matches, Winmar was named in St Kilda's Team of the Century in 2003 and was inducted into the West Australian Football Hall of Fame in 2009. An Indigenous Australian, he was the first Aboriginal footballer to play 200 games in the AFL and was named in the Indigenous Team of the Century in 2005. He was involved in several incidents of racial vilification during his career and a photograph of Winmar responding to one such incident during the 1993 season has been described as one of the most memorable images in Australian sporting history.