 Born in Burnley to Bernard and Mary Mullin, Mullin started his career with Accrington in 1995, making his first-team debut before being released.He then played for Darwen, Trafford, and spent two-and-a-half years at Clitheroe before joining Radcliffe Borough in the summer of 1998.Two years later, in August 2000, he rejoined Stanley, newly promoted to the Northern Premier League Premier Division as champions, for a fee of £15,000, after a bid of £10,000 had been rejected the previous season.