Day was signed by Grays Athletic on a two-year deal from Welling United on 15 May 2007. He had formerly played for Arsenal as a trainee, making the first team subs bench once for the Gunners, he then moved to Bournemouth for a fee of £20,000. He then moved to Dover Athletic in 2001, Welling in 2004, Grays in 2007 and Dartford in 2008 after his contract with Grays Athletic was terminated by mutual consent on 22 August 2008.
Day was announced as the new player-manager of Conference South club Welling United in November 2009. After steadily consolidating the club, Day guided Welling United to the Conference South title in 2013, promoting the club to the highest tier in non-league football. He joined Ebbsfleet Utd as their manager in December 2014 the following day after Welling Utd won 2-1 at AFC Telford.