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.

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.

Nicky grew up on an Aboriginal reserve in Western Australia’s Wheatbelt,[7] near the town of Pingelly,[5] in a windowless shack made of corrugated iron with a dirt floor, no running water or sewerage.

[11] After an outstanding season in 1989, Winmar won St Kilda's best and fairest award and was also named in the VFL's Team of the Year on a half-forward flank.

[17] In round four of the 1993 season, Indigenous players Winmar and Gilbert McAdam were racially abused by Collingwood supporters, eventually being awarded two and three Brownlow Medal votes in a game St Kilda won by 22 points.

[15] At the end of the season, Winmar was also refused clearance by St Kilda to play in the Aboriginal All-Stars game, held at Marrara Oval in Darwin.

[20] Winmar played his 200th game for the club in round 17 of the 1997 season, against the Brisbane Lions at Waverley Park, becoming the first Indigenous player to reach the milestone in the AFL.

After the match, Winmar's manager, Peter Jess, was criticised for making comments in an interview with radio station 3AW suggesting that Aboriginal players were unable to cope with the pressures introduced by "white society".

[26] Winmar played a total of 21 games for the club, kicking 34 goals, before retiring from the Western Bulldogs at the end of the 1999 season, halfway through a two-year contract, citing issues with a commitment to training and injuries.

[29] However, after the incident two years later when Michael Long made a complaint against Damian Monkhorst for racial abuse, Winmar felt stronger, owing to the support received by the AFL.

[34][29] The photograph is reproduced in The Game That Made Australia, a mural painted by Jamie Cooper and commissioned by the AFL in 2008 to celebrate the 150th anniversary of the origins of Australian rules football.

[37] In March 2023, during Round 2 of the 2023 AFL season, Western Bulldogs player Jamarra Ugle-Hagan received a racist remark from a St Kilda supporter when walking off the field at the end of the game.

During the following week's game, in celebration of one of five goals he scored, Ugle-Hagan lifted his shirt and pointed to his skin whilst looking at the crowd, emulating Winmar's gesture.

[41] Clark was forced to return the jumper to Winmar, which was later donated to the National Museum of Australia, where it featured in Off the Walls, an exhibit of Indigenous Australian art.

[8] Having previously worked with Denfam (a Melbourne-based construction business) and as a shearer, Winmar was employed in the mining industry and was living in Brookton, Western Australia, as of May 2012.

[56] Winmar's memoir, My Story: From Bush Kid to AFL Legend, was co-written with Matthew Hardy and published by Allen & Unwin on 31 October 2023.

[59] Winmar's player statistics are as follows:[2] Klugman, Matthew; Osmond, Gary (2013), Black and proud : the story of an iconic AFL photo, Sydney, NSW NewSouth Publishing, ISBN 978-1-74223-405-2