 On 9 November 1981, Rawsthorne was appointed an auxiliary bishop of the Archdiocese of Liverpool and titular bishop of "Rotdon" by Pope John Paul II.He received his episcopal consecration on the following 16 December 1981 from Archbishop Derek Worlock, with bishops Kevin O'Connor and Anthony Hitchen serving as co-consecrators.Following the resignation of Bishop Gerald Moverley, Rawsthorne was appointed the second Bishop of Hallam on 4 June 1997.