In 2003 Chapman officially joined the Geelong senior team playing all 22 games of the season. Chapman played his best game for the season in round 7 against the West Coast Eagles where he kicked 4 goals, Chapman also kicked a last minute game-winning goal against Richmond in Round 15. Chapman would play his 50th career game in round 21 against the Brisbane Lions. At the end of the 2003 season Chapman would be named best team and constructive player, he would also finish 8th in Geelong's Best and Fairest.