After appearing in around 200 league games for Scunthorpe United and Lincoln City, Justin Walker spent a single season at Exeter City in 2002/03 which ended in the club’s relegation from the Football League. He then signed for Cambridge United with whom he suffered the same fate.   

Representing England at both schools and youth level, Justin became an apprentice at Nottingham Forest and soon turned professional. Without making a first-team appearance Justin left Forest in May 1997 for Scunthorpe United where he had made his league debut when on loan. Appearing in over 130 league games over the following three seasons, Justin then headed down the A15 in June 2000 to spend two seasons with Lincoln City.    

On leaving Sincil Bank, Justin arrived at Exeter City in August 2002 and promptly made his debut in the opening game at Shrewsbury Town. Although the Grecians soon struggled, Justin clocked-up 45 appearances in all competitions scoring half-a-dozen times along the way. However, in spite of his efforts, the team continued to flounder and Justin was to appear against Southend United on 3 May 2003 as the Grecians were relegated from the Football League. 

Justin, for his part, remained in the Football League when he agreed terms with Cambridge United in June 2003. After around twenty games, he had nine games on loan with York City early in 2004 as the Minstermen battled against joining Exeter City in the Conference. However, although Justin was back at Cambridge when York’s relegation occurred, he was to suffer the same fate with Cambridge’s own relegation at the end of 2004/05. 

Again dodging playing in the Conference himself, Justin appeared for Chester City during 2005-06 season before, after just 21 league appearances, moving on to Ilkeston Town followed by AFC Halifax and, in February 2009, Hucknall Town. He later became an academy coach at Derby County where, between managers in November 2020, he was briefly part of the team that looked after the first-team on an interim basis. Thereafter, in November 2022, Justin became assistant head coach to Liam Rosenior at Hull City.