Underwood began his career with Carshalton Athletic, and after spells at Sutton United, Dorking and Molesey, he moved to Enfield.
Underwood was signed by Luton Town in March 2004,[2] but was injured just 19 minutes into his debut – two days after joining the club.
He had a superb season during the 2004–05 campaign as the Hatters won the Football League One Championship, with Underwood playing mainly on the left-wing.
Despite not playing a game the previous season, Underwood had shown enough ability during his two years at Kenilworth Road to persuade then Hatters boss Mike Newell to give him a new two-year contract, which he duly signed, keeping him at Luton until the summer of 2009.
[3] Underwood, however, never made a full recovery from his illness, and spent his last two seasons without playing a single game for Luton.