Another product of the Norwich youth team, Truro-born Justin signed professional forms at the beginning of the 1994-95 season. He had been first spotted by the Canaries as a 10 year old playing for Camborne Lions in the Canary Cup. A regular in the Reserves, Justin scored 5 goals in 25 games (6 as substitute) but never made the first team. He was released by Norwich in May 1996 and followed former manager Martin O'Neill to Leicester City. He was in good company at Filbert Street sharing Carrow Road memories with Spencer Prior, Mark Robins and Robert Ullathorne

He was given a free transfer the following summer by O'Neill as Harrington was unable to displace Heskey, Claridge, Robins and Marshall in the Leicester attack. He joined Bournemouth - another club with strong Carrow Road connections currently manifesting in manager Mel Machin .

Justin was released by Bournemouth at the end of the 1997/98 season. After a spell with Portleven who compete in the Jewson South Western League Championship, Justin moved to rivals St Blazey in the summer of 2000. Justin has also played for Cornwall against Devon.