Saint-Jean-de-Maurienne (San Giovanni di Moriana) is a commune in the Maurienne, the valley of the River Arc. It is the capital and name of a canton and an arrondissement (formerly in Haute Savoie) of the present Savoie département, in the southeastern Rhône-Alpes region of France. It was also an episcopal see of Savoy during the Ancien Régime and again from 1825 to 1966. Its original name was simply Maurienne, or Moriana in Latin.
The Duchy of Savoy, which had been a French-speaking province under the sovereignty of the Kingdom of Piedmont, was invaded by Revolutionary France and later permanently annexed. The diocese of Saint-Jean-de-Maurienne was formally suppressed in 1801 by the Holy See in accordance with the Napoleonic Concordat of 1801.
In 1825, some years after the territory had been passed back to Piedmont by the Congress of Vienna, Maurienne was restored as a diocese along with Tarentaise, with territory taken from Chambéry. By plebiscite of 22 April 1860, Savoy passed to French sovereignty again.
In 1966 the two dioceses were once more amalgamated with the metropolitan see of Chambéry, to which their titles were at the same time united.