Prior to joining WWE, Farrelly wrestled on the European circuit and was a two-time International Heavyweight Champion during his tenure in Irish Whip Wrestling (IWW).

After becoming part of the WWE main roster in 2009, he would go on to be a four-time world champion in WWE, having held the WWE (World) Championship three times and the World Heavyweight Championship once. He is also a two-time United States Champion. In addition to these championships, he has won the 2010 King of the Ring tournament, the 2012 Royal Rumble match and the 2015 Money in the Bank ladder match, making him only the second wrestler (after Edge) to achieve all three accomplishments.