It extends along the west of England from the Ribble River in the south of Preston to the Scottish border, comprising the counties of Cumbria and much of Lancashire.

Central organisations of the diocese include the residential youth centre Castlerigg Manor, the Diocesan Youth Service, the Education Centre, Catholic Caring Services and others including the monthly diocesan newspaper, The Voice.

Areas in the diocese include the city of Preston; a city with an uncharacteristically high Catholic population - the highest anywhere in England & Wales in fact, due in no small part to the fact that the Protestant Reformation never took hold in Preston to the same extent as it did in other places.

On 12 February 2018 it was announced that Pope Francis had appointed Canon Paul Swarbrick, parish priest of Christ the Good Shepherd, Workington, to be the seventh bishop of the diocese.

On 9 April 2018, Paul Swarbrick was consecrated and installed as Bishop of Lancaster at St Peter's Cathedral; Vincent Cardinal Nichols attended the ordination.