Forbes began his career at Sittingbourne, before being purchased by Millwall for £50,000. He made five league substitute appearances during his time with Millwall, before signing for Colchester United. He had his best spell whilst with the U's, helping them secure promotion via the 1997–98 Division Three playoffs and scoring four goals in 56 league appearances, 36 of which were starts. He went out on loan during the 1998–99 season to Peterborough, where he made three appearances before returning to Colchester. He was signed by Stevenage Borough in April 2000 after being released, and later signed for Dagenham & Redbridge in the summer of 2000. He subsequently joined Hendon and also made appearances for Billericay Town. He was last seen playing for Eastleigh in 2007.