The Diocese of Carlisle was created in 1133 by Henry I out of part of the Diocese of Durham, although many people of Celtic descent in the area looked to Glasgow for spiritual leadership. The first bishop was Æthelwold, he was the king's confessor and became prior of the Augustinian priory at Nostell in Yorkshire. Carlisle was thus the only cathedral in England to be run by Augustinians instead of Benedictines. This only lasted until the reign of Henry III however, when the Augustinians in Carlisle joined the rebels who temporarily handed the city over to Scotland and elected their own bishop. When the revolt was ended, the Augustinians were expelled.
The seat of the diocese is the Cathedral Church of the Holy and Undivided Trinity in Carlisle.
The Diocese covers the most of the non-metropolitan county of Cumbria; Alston Moor is part of the Diocese of Newcastle, and the former Sedbergh Rural District is part of the Diocese of Bradford. The diocese originally only covered the northern parts of Cumberland and Westmorland, and expanded to cover the entirety of these, as well as the Furness and Cartmel areas of Lancashire, in 1847, from part of the Diocese of Chester, although this did not take effect until 1856.