As a player, he was as a midfielder between 1996 and 2013. He has previously played for Leicester City where he played in the English Premier League before moving on loan to Birmingham City and Grimsby Town. He signed with Grimsby on a permanent basis in 2001, and he remained with the club until joining Bristol Rovers in the summer of 2004. Campbell became club captain at Rovers and in 2012 he briefly managed the club on a caretaker basis before leaving the club at the end of the season. At international level, he won 14 caps for the Scotland under-21 team. In 2012 he moved to the USA and signed with the Tampa Bay Rowdies where he played for one season before becoming Assistant Coach. In August 2015 he assumed the role of Head Coach after the midseason firing of Thomas Rongen, he stayed in this position until 2018.