Walker made his professional debut for Coventry City on 28 December 2008 as a substitute in a 2–0 Championship win against Sheffield Wednesday.
Walker joined Nuneaton Town on loan in October 2009, before joining them on a permanent deal on 1 April 2010 after being released by Coventry City. Walker remained at Nuneaton for several seasons making over 250 appearances and was part of the promotion winning side to the National League during the 2011/ 2012 season.
The midfielder joined Gavin Cowan at Solihull Moors during the 2015/16 season and was part of the title winning season that won the league by 10 points. Adam joined Brackley Town in the summer of 2015 and has remained at the club for the last two seasons during that period he made over 70 appearances winning the FA Trophy.