O'Connor was born in Dublin and joined English club Stoke City in 1996 after being spotted by the club's Irish base scouts. He made his debut in the 1998–99 season before becoming a regular in the team in 1999–2000. He scored eight goals in 55 appearances as Stoke reached the play-offs where they lost to Gillingham although he did play in the 2000Football League Trophy Final where Stoke beat Bristol City 2–1 and his performances during the season earn him the player of the year award. He played 54 times in 2000–01 for Stoke scoring ten goals as they again failed in the play-offs losing to Walsall. He played in 50 matches in 2001–02 as Stoke finally won promotion via the play-offs, beating Brentford 2–0 in the 2002 Football League Second Division play-off Final. He played 47 times in 2002–03 helping Stoke avoid relegation before he turned down the offer of a new contract. He moved to West Bromwich Albion in summer 2003 for a fee of £250,000 and made his debut in the 4–1 defeat to Walsall. He spent a successful three-month loan spell with Burnley in 2004–05. That season he made only two substitute appearances for West Bromwich Albion and moved to Burnley permanently to pursue first-team football, signing on transfer deadline day in 2005 for a £175,000 fee where he became a popular player with the fans. His form at the start of the 2006–07 season at Burnley was among the best of his career. However, by the start of the 2007–08 season he seemed to be relegated to a squad player's role. The departure of Steve Cotterill as Burnley manager brought Owen Coyle in and he immediately restored O'Connor to the starting eleven. O'Connor responded by resuming his previous good form as the team's results improved. He was offered a new contract at the end of the 2007–08 season but when O'Connor asked for more time to consider his options, Coyle withdrew the offer and released him. O'Connor confirmed in an interview on BBC Radio Lancashire on 23 May that he was about to start a coaching course before deciding on his future. O'Connor confirmed his move to Championship side Sheffield Wednesday on 27 June 2008 following a month of speculation surrounding the move in the press. He joined the club on a free transfer under the Bosman ruling after turning down the offer to extend his stay at Turf Moor.
Coaching
On 10 January 2012, O'Connor signed with American third-tier side Orlando City of USL Pro. He became a player-coach in 2013 with the team. He then became manager of Louisville City. In March 2017, O'Connor extended his contract with Louisville City through the 2020 season. On 29 June 2018 Louisville City announced that O'Connor would depart the club after its match against New York Red Bulls II the next day to become head coach of Orlando City SC in MLS, replacing Jason Kreis, who was sacked two weeks earlier. A trio of players – George Davis IV, Paolo DelPiccolo and Luke Spencer – would serve as player-coaches on an interim basis until a replacement was announced. He was sacked at the end of the 2019 season with the team having missed out on playoffs again and remaining 11th in the Eastern Conference.
