In 2005, Campbell followed his former manager, Robert Reilly, to Somerset Park and in his first season he made 23 appearances in all competitions.
The 2008-09 season was far more successful for Campbell, with him racking up 37 appearances and scoring his first competitive goal for the club in a 3-0 away win over Arbroath.
In January 2009, Campbell was struck by Kilmarnock's David Fernandez in an Ayrshire derby that was being shown on Sky Sports.
Campbell was once again instrumental to the club's success throughout the 2010-11 campaign, playing 36 times and scoring another goal, this time in the Challenge Cup against Cowdenbeath, as well as featuring in Ayr's famous victory over Hibernian in the Scottish Cup and in all of the club's play-off games, which saw Ayr promoted back to the First Division.
The 2011-12 season was more difficult for Campbell as he only featured 13 times, missing most of Ayr's impressive cup runs.