Paul Shields started his professional career as a 17 year old with Raith Rovers. Kenny Dalglish signed him for Celtic in March 2000 for £100k and he went on to spend most of his time with the club out on loan. He hardly played for the U21's or U18's and after extended loan periods to Queens Park, Clydebank and Queen of the South. Whilst at Clydebank he made a verbal attack against Martin O'Neill, the new manager.

He left on a free and went to join Clyde in March 2003. He was released at the end of that season and picked up by Forfar on a free as a part-timer(he also worked as a postman). He did well for Forfar and this attracted a bid from Gillingham, to whom he moved in August 2005 for £25k. At Gillingham he got full time football again getting games mostly as a sub but he gradually forced himself into the starting line-up.

He was released at the end of 05/06 by mutual consent and moved back to Scotland and to play for Livingston. He had a loan period at the end of 06/07 with Ayr Utd. In July 2007 he was listed as a transfer to Ostersunds FK - 2nd Div Swedish side to July 08.

Signed for Junior club Bo'ness United in Summer 2009.