Farrell started the 2010 season on a dual registration loan at Widnes. He made a try scoring home debut against Barrow. Widnes head coach Paul Cullen praised Farrell, saying that "These are hardened professionals who have been around the block a few times and they know how to knock some young players about, and he was still going just as strong at the end of the game.” Wigan Head Coach Michael Maguire gave Farrell his Wigan first team debut in the victory over Wakefield Trinity on 5 April, coming off the bench and scoring a try.
He played in the Super League Grand Final for Wigan coming away with a victory.
Farrell played for Wigan from the substitutes' bench in the 2011 Challenge Cup final victory over Leeds.
After several outstanding seasons Farrell has gone on to establish himself as one of the games most consistent back row forwards. His performances have even drawn praise from the Australian media.
Farrell played in the a Rugby League World Cup warm up match v Italy at Salford on 19 October 2013 when England were beaten 15 -14, and should figure for England in the Rugby League World Cup matches in October & November 2013.