He joined Torquay United in August 1999 and later that month, on the opening day of the season, scored on his league debut against Shrewsbury Town at Gay Meadow.
After a first season in and out of the starting line-up, but with some notable moments, including as a goal from a 30-yard free kick at Loftus Road in the FA Cup third round tie against Queens Park Rangers in December 1999, O'Brien fell out of favour with manager Wes Saunders.
With Saunders sacked, O'Brien returned to the first team squad under new manager Colin Lee, playing four times as a substitute before the end of the season.
He appeared as a late substitute for Tony Bedeau on 11 August 2001, as Torquay lost 1–0 away to Bristol Rovers, but was released at the end of that month.
[2] He returned to the Droylden side in October 2005, playing his final game for them that season on 12 December as Droylsden lost at home to Workington.