	Mahon began his career with Wolverhampton Wanderers, progressing through the youth ranks with the club and playing regularly for the youth team. He was released by Wolves at the end of the 1995–96 campaign, having made no first-team appearances. In July 1996, he signed for Hereford United of Division Three on a free transfer, making his first professional appearance in the club's 1–0 victory over Doncaster Rovers on 24 August 1996.<ref name="Games played by Gavin Mahon in 1996/1997"></ref> Mahon scored the first goal of his career during the same season, in a 3–0 win against Rochdale. Despite featuring seven times during the early stages of the season, he did not make any further first-team appearances from November onwards, with Hereford suffering relegation to the Conference National at the end of the campaign. Mahon remained at Hereford for the 1997–98 season, playing in all 42 league matches as Hereford finished the season in sixth place.