O'Shea was seeded at the 2012 BDO World Championship, O'Shea put his successful run in the tournament down to his work with professional sports mind coach and hypnotherapist Stephen McKibben from Belfast. He beat Steve West in the first round, hitting a 140 checkout and 142 checkout in consecutive legs at the end of the match, before defeating Ross Montgomery in the second round. He then beat defending champion Martin Adams 5–2 in the quarter-finals, hitting a 170 checkout in the fourth set and thanked mind coach Stephen McKibben for enabling him to at last beat Martin Adams in a major tournament. O'Shea followed this up with a 6–5 victory over Dutch débutant Wesley Harms to reach his second World Championship final, where he was defeated by another Dutch débutant, Christian Kist, 7–5.