Mills was released by Crawley on 8 May 2012. Mills described his release as 'amicable' and wished the club well for the future. Mills was linked with his former club Rotherham United.
In July 2012, Mills was linked with French Ligue 2 side Boulogne after the club invited Mills for negotiations. However, Mills rejected a chance to move to France after deciding to stay in the UK for family reasons. In August 2012, Mills joined conference side Macclesfield Town.
On 27 March 2012, Mills was involved in a post-match fight against Bradford City and was shown a red card along with four other players (one Crawley and three Bradford). As a result, he was given a three match ban as well as being stripped of his captaincy and fined two weeks' wages. Both Mills and Claude Davis (one of the players involved in the fight) wrote a letter of apology and said: