Career
He has also played for , and Ayr United. In January 2007, O'Brien signed a pre-contract agreement with , moving to Tayside in May 2007. At the end of the 2007–08 season, O'Brien signed a one-year contract extension with the Dens Park side.
O'Brien failed to have his contract renewed when it expired in 2009. On 15 June 2009, Ayr United announced that they had signed O'Brien. O'Brien left the Honest Men on 3 August 2009, after not being selected to play against his old club on 1 August 2009.
O'Brien met with the manager Brian Reid, and after a short discussion he left the club. He rejoined his home town team, , on 6 August 2009. After his contract expired at Stirling, he joined manager Allan Moore at new club Greenock.
O'Brien signed on for another season in May 2012. He again signed a one-year deal in May 2013. He left in the summer of 2014 after failing to recover from an injury sustained at Celtic Park.
