Castle began his career at AFC Bournemouth aged nine before moving to Reading in 2001 where he broke into the reserve team at 15.
In September 2005 he moved to St. Albans City on a one-month loan and made six appearances in total before returning to Reading on 11 October.
[10] Castle remained at Bashley for three and a half years and helped the club to promotion to the Southern League Premier Division during the 2006–07 season.
[12] After a brief stay with Totton, Castle joined Southern League Division One South & West rivals Gosport Borough in June,[13] remaining there for one season before switching to Lymington Town on 1 July 2011.
[15] Following his release he joined GE Hamble until the end of the 2011–12 season[6] before returning to Southern League football with Winchester City in June 2012.