In his dual capacity as prince and as bishop, the prince-bishop also administered the Diocese of Konstanz, which existed from about 585 until its dissolution in 1821, and whose territory extended over an area much larger than the principality.

While the Prince-Bishop was the secular ruler in his prince-bishopric, his authority in his diocese was limited to the pastoral duties exercised by any bishop.

However, Constance fell to the Counter-Reformation promoted by the Habsburgs, who eventually abolished its status as a free imperial city and incorporated it into their Further Austrian possessions in 1548.

The huge diocese of Constance suffered heavily during the Reformation and it lost several hundred parishes, convents and other Catholic foundations which were suppressed by the various states, free imperial cities and cantons in Swabia and Switzerland that had become Protestant.

As a result of these changes, the cantons of Obwalden and Nidwalden, parts of Uri, Glarus and Zürich were assigned provisionally to the administration of the Diocese of Chur, an arrangement still enduring.