Marshall is a product of the Manchester City Youth Academy which he joined when he was 11 years old in the 2006/07 season. At the end of this season he signed his first professional contract.
He signed for Walsall in June 2010, then Conference North oufit FC Halifax Town in July 2012. He moved up a division when he joined Stockport County in February 2013, returning to Halifax after being released from Edgeley Park as the Shaymen were promoted to the Conference National. He made 39 appearances in the 2013/14 campaign, helping the club to qualify for the play-off semi-finals, where they lost to Cambridge United. He remained a key player in the 2014/15 campaign, scoring three goals in 42 appearances.
Paul then signed for National League North side Bradford Park Avenue in May 2015. Avenue finished 14th in their 2015/16 sampaign.He then signed for Alfreton Town in October 2016.