Originally (from 1068) the diocese served all the area of Gulating: the modern counties of Hordaland, Sogn og Fjordane, Rogaland, Vest-Agder and Aust-Agder - and the regions of Sunnmøre, Valdres and Hallingdal.
The discovery at Selja in 996 of the supposed remains of St. Sunniva and her companions led King Olaf Trygveson to build a church there.
In 1275 Magnus VI of Norway founded a great church, as his new royal chapel at Bergen, to receive a relic of the Crown of Thorns.
Bishop Thorleif Olafssön (1430 – 1450), having joined Olaf Nilssön at the Brigittine Convent of Munkalif, was killed there by the Germans of the Hansa on 1 September 1455.
The last Catholic bishop, Olav Torkelsson (1523 – 1535) allowed the Cathedral of Christ Church, the Royal Chapel of the Apostles, the Dominican convent, and other ecclesiastical buildings in Bergen to be destroyed, when the fortress of the Bergenhus was enlarged.
It dealt with the collection of money for the maintenance of the Council of Basle, the superstitious observance of Saturday, which was forbidden, and unauthorized begging on the part of religious.