The Diocese of Saint-Malo is a Roman Catholic diocese located in the region of Brittany, France. Established in the 3rd century, it is named after Saint Malo, a Breton bishop and the city's patron saint. The diocese covers the area around the city of Saint-Malo and includes several surrounding towns and communities. The diocese is part of the Metropolitan Archdiocese of Rennes and plays a significant role in the spiritual life of its local population. It is responsible for various parishes, religious education, and community services, promoting the teachings of the Catholic Church in the region.