Exeter confirmed on 19 May 2009 that they had received an offer – believed to be around £200,000 – for Moxey from Derby County which they rejected, though they did give an indication of a more acceptable transfer fee. An improved offer, believed to be around £300,000, was accepted on 8 June 2009. Moxey joined Derby on a three-year contract on 26 June 2009, and was given the number 21 shirt. He made his first appearance in the 2–1 win over Peterborough United in which he was voted man of the match by the Derby County supporters. Moxey spent the majority of his first season at Derby battling with Jay McEveley to be the club's first-choice left back and eventually finished the season with 31 starts from the clubs 51-game programme.