[1] He played his early career in country football and represented Bendigo in the TAC Cup before catching the eye of talent scouts.

For the rest of 2004 and 2005, Andrew struggled to reproduce the stunning form he displayed on debut, and it wasn't until 2006 that he started to play consistent football for the Carlton senior side.

In 2006, Andrew had a number of very successful games as a tagger (often tagging the opposition's premier midfielder), and also provided much run off half back.

[6] Additionally, in round 18 against Essendon, Walker took a huge specky over Essendon player Jake Carlisle, which was considered by many football observers, including The Age's Rohan Connolly,[7] and both match-day coaches, Brett Ratten and James Hird,[8] to be one of the greatest marks of all-time – although ultimately it did not win the season's Mark of the Year award.

Despite this, in July 2016 he became the first Aboriginal footballer to play 200 games for Carlton,[12] reaching the milestone in their round 15 loss to Collingwood.

[13] In the following months, he continued to struggle with injury, and in August announced his intention to retire after the round 20 match against St Kilda at the Melbourne Cricket Ground.

[14] Following his retirement, Walker was engaged by Carlton as a "Development & Integration" coach, specialising in helping first year players in their transition to becoming professional footballers.