Career
After spending his youth career at Everton and Liverpool, Mullin moved to Spain to sign for Racing Santander in the summer of 2011. However, the move fell through due to serious financial problems at the Cantabrian club The move affected Mullin, as he was disheartened and questioned himself around his football career, quoting: ""where do I go from here?""
Despite things not working out for Mullin, Huddersfield Town"s youth coach David Rowe invited him to the squad.
There, Mullin was signed to Huddersfield Town in 2012 and often impressed at U18 and U21 level that he signed a one-year contract by the club
However, at the end of the 2013-2014 season, Mullin was released by the club, without ever making a first team appearance. After a successful trial period he signed for Morecambe on a short term contract in August 2014.
He made his professional debut coming on as a second-half substitute in the League Cup first round defeat to Bradford City on 12 August 2014. After scoring three goals in the first seven matches, Mullin signed a three-year contract with the club in mid-September.
Then on 31 October 2014, Mullin would end his eleven games without scoring despite losing 2–1 to Acrrington Stanley.