[2] Whilst in Germany he played football in an army tournament and was spotted by scouts from Celtic and he joined them along with Gary Holt.
[2] In 1997–98 Stoke suffered relegation to the Second Division, however Whittle did manage to win the player of the year award despite playing in just 20 league matches.
[3] He was recruited by Warren Joyce in 1998 while City were battling relegation from the Football League and became an integral part of the "Great Escape" team.
Whittle joined Grimsby in time for the start of the 2004–05 season after it became apparent that first team opportunities would be limited at Hull due to an influx of new players and that he would lose the captaincy as a result.
In April 2008 it was decided by the club that they would not offer Justin Whittle an extension to his contract and he left on good terms in May after playing some of his best football with the Mariners.
Whittle signed for North Ferriby United in March 2009, slotting straight into his usual central defensive position.
Following the resignation of John Anderson on 11 September, Whittle took caretaker control of the first team alongside club captain Paul Foot.