In 2003, Farrell began playing for the Professional Darts Corporation in Irish based events. In 2006 however, Farrell became a member of the PDPA and began playing on the pro tour. Though he has yet to play in a PDC major apart from the UK Open, Farrell has come close to doing so on numerous occasions. He came close to qualifying for the 2009 PDC World Darts Championship, falling at the final hurdle to Mark Stephenson. He also came close to qualifying for the 2009 World Grand Prix in Ireland, where having taken one of the four Irish qualifying spots ahead of the Players Championship in Austria, Farrell missed out on a countback following Jacko Barry's run into the last 32 stage in the first Players Championship who took the fourth spot ahead of Farrell who reached the last 64 stage in both tournaments.