Luke O’Brien signed on a free transfer from Bradford City in January 2012 with Exeter City taking over the contract that he had with the Yorkshire club. He played just three times for City before departing for Oxford United. 

Luke joined Bradford City’s centre of excellence when he was eight-years-old, became a trainee in 2005 and a professional in July 2007. He made his debut in the Football League Trophy in September 2007 and played regularly for the first-team from October 2008 onwards. Signing a new contract in June 2010 Luke had played 149 times in all competitions by January 2012 when, after starting to feature on a less-regular basis, he was transferred to Exeter City to replace the recently-departed Scott Golbourne.

Although there had been a financial agreement with Bradford City, the Grecians had only taken over the final remaining months of Luke’s Valley Parade contract. He was to make a belated debut against Stevenage on 3 March 2012 before playing twice more that week in what was, in essence, an three-games-in-eight-days Exeter career. Luke wasn’t re-engaged at the end of the season and signed for Oxford United.

Luke had a single season at Oxford before moving on to Gateshead in 2013/14. From there he was to play non-league football in Yorkshire with Thackley, Bradford Park Avenue, Shaw Lane Aquaforce and Goole before returning to Thackley in late 2016. Luke later worked as a satellite installation engineer and coached an under-10s team.