Boyle was born in Radcliffe, Lancashire (now Greater Manchester) into a working-class Irish Catholic family. His mother was from Ballinasloe, Co Galway, and his father was born in England, but to an Irish family. For a while, Boyle seriously contemplated priesthood and attended religious school as a teenager. Instead, he studied at Thornleigh Salesian College in Bolton, and at the University of Wales, Bangor. While at university, Boyle dated the actress Frances Barber.