The Diocese of Quimper (–Cornouaille) and Léon is a Latin Church ecclesiastical territory or diocese of the Catholic Church in France. In 1853, the name was changed from the Diocese of Quimper (–Cornouaille) to the Diocese of Quimper (–Cornouaille) and Léon.

The Archdiocese of Rennes, Dol, and Saint-Malo is a Latin Church diocese of the Catholic Church in France. The diocese is coextensive with the department of Ille et Vilaine. The Archdiocese has 8 suffragans: the Diocese of Angers, the Diocese of Laval, the Diocese of Le Mans, the Diocese of Luçon, the Diocese of Nantes, the Diocese of Quimper and Léon, the Diocese of Saint-Brieuc and Tréguier, and the Diocese of Vannes.