was born in Dublin, the son of Rita (née Monaghan), a housewife, and Eamon Farrell, a footballer who played for Shamrock Rovers F.C. and owned a company importing and exporting canned goods in Dublin City. He was raised as a Roman Catholic. His uncle Tommy Farrell also played for Rovers. Farrell has two sisters, Claudine (who is his personal assistant) and Catherine, and a brother, Eamon Jr. When he was ten, the Farrells moved to Castleknock, a Dublin suburb. Farrell was educated at St. Brigid's National School Castleknock followed by Castleknock College and Gormanston College. Farrell unsuccessfully auditioned for the Irish group Boyzone when he was still unknown. Farrell attended The Gaiety School of Acting, but dropped out and was cast in the part of Danny Byrne on Ballykissangel, a BBC television drama. Farrell appeared on the show seven times from 1998 to 1999. He was inspired to try acting after being brought to tears while watching E.T. the Extra-Terrestrial.