Background
O'Brien is a central midfielder and comes from a footballing background as his father Derek played for Shamrock Rovers from 1981 to 1983 and his uncles Fran and Ray both played for Ireland.
O'Brien is a central midfielder and comes from a footballing background as his father Derek played for Shamrock Rovers from 1981 to 1983 and his uncles Fran and Ray both played for Ireland.
Early years O'Brien played for Belvedere at youth level and made several appearances at under-age level for Ireland. He began his senior career at Shamrock Rovers making his debut on 7 May 2003 in a League of Ireland Cup tie against Bray Wanderers. Bohemians He never showed the same form at Bohemians and midway through the 2006 season, he returned to Shamrock Rovers on loan where he helped the Hoops to the First Division title.
After his loan spell finished at the end of the 2006 season, he returned to Bohemians but had failed to appear for the first team during the 2007 season only making under-21 appearances. Shelbourne In need to restart his flagging career, O'Brien departed Bohemians to sign on loan for nearby rivals Shelbourne in July 2007. O'Brien permanently joined Shelbourne on 29 November 2007.
He finished as a First Division runner-up with Shelbourne in both 2008 and 2009 as Shelbourne narrowly missed out on promotion during both seasons. O'Brien was released by Shelbourne following the conclusion of the 2009 season. In his 3 seasons at Shelbourne he made 85 league and cup appearances scoring 5 goals.
Bray Wanderers In March 2010 O'Brien returned to football signing for Bray Wanderers. He scored twice on his Bray debut in the EA Sports Cup against Drogheda United but failed to hold down a first team place after this. O'Brien parted company with Bray Wanderers in July 2010 after making 5 appearances for the club.
On 27 August 2010, O'Brien returned to Shelbourne after training with the club for a number of weeks. Drogheda United Prior to the start of the 2011 League of Ireland season, O'Brien joined Drogheda United. After nailing down a starting place in Mick Cooke's midfield, O'Brien signed a new one-year contract for the Drogs, keeping him at United Park until the end of the 2012 season.
Dundalk He joined Dundalk on the final day of the 2012 July transfer window. His father had played for the Lilywhites in the 1970s.