 His consecration to the episcopate took place on 29 June 1993, the principal consecrator was Basil Hume, Cardinal-Archbishop of Westminster and the principal co-consecrators were John Patrick Crowley, Bishop of Middlesbrough and Patrick Joseph Casey, Bishop Emeritus of Brentwood.Following of the sudden death of John Brewer while in office, O'Donoghue was appointed the Bishop of Lancaster on 5 June 2001, and installed at St Peter's Cathedral, Lancaster on 4 July 2001.His portrait was painted for Westminster Cathedral in 2002 by Christian Furr.