Farrelly's inspiration into a professional wrestling career came from watching both British wrestling from ITV's World of Sport and American wrestling from the World Wrestling Federation on Sky One. On the advice of Bret Hart, Farrelly began training in Larry Sharpe's Monster Factory wrestling school in April 2002, alongside Tank Toland, Cliff Compton and Cindy Rogers. Six weeks later he officially debuted as a fan favorite under the name Sheamus O'Shaunessy against Robert Pigeon. It was during this time that he developed the nickname the "Irish Curse" after low-blowing an opponent. He soon suffered a serious neck injury after botching a hip toss which sidetracked his career for two years.

ACHIEVEMENTS/CAREER HIGHLIGHTS:
4x WWE World Heavyweight Champion
3x WWE Raw Tag Team Champions
3x WWE United States Champion
King of the Ring 2010 winner
Royal Rumble 2012 Winner