Maddy progressed through the youth ranks at Cardiff City and spent three years in the first-team squad before joining rivals Swansea City in 1983. He went on to have spells with Hereford United (where he had earlier played on loan) and Brentford before a £15,000 move to Chester City in the summer of 1987. The following March he returned to Hereford on a free transfer to end his Football League career.
He later played in Malta for Hamrun Spartans.
Maddy was twice capped by Wales at under 21 level, in matches against Netherlands and Norway.