The Roman Catholic Diocese of Saint-Étienne is a Latin Rite Catholic diocese in France, based in the city of Saint-Étienne in the Loire department.
It was established on 26 December 1970 out of the Archdiocese of Lyon-Vienne and consists of the arrondissements of Saint-Étienne and Montbrison, thus constituting the greater part of the department of the Loire.
The seat of the bishop is Saint-Étienne Cathedral, dedicated to Saint Charles Borromeo (Cathédrale Saint-Charles-de-Borromé de Sainte-Étienne).