The Roman Catholic Diocese of Nice is a diocese of the Latin Rite of the Roman Catholic church in France. The diocese comprises the Départment of Alpes-Maritimes. The diocese is a suffragan of the archdiocese of Marseille. The current bishop is Louis Albert Joseph Roger Sankalé, appointed in 2005. By tradition, Nice was evangelized by St. Barnabas, sent by St. Paul, or else by St. Mary Magdalen, St. Martha, and St. Lazarus. St. Bassus, a martyr under Emperor Decius, is believed to have been the first Bishop of Nice. The See of Nice in Roman Gallia Narbonensis existed in 314, since the bishop sent delegates to the Council of Arles in that year.
The first bishop historically known is Amantius, who attended the Council of Aquileia in 381. Cimiez, near Nice, had also an episcopal see around 260, held in the middle of the fifth century by St. Valerianus; a papal rescript of St. Leo the Great, issued after 450 and confirmed by pope Saint Hilarus in 465, united the sees of Nice and Cimiez. This newly-formed see remained a suffragan of Embrun up to the French Revolution. St. Anselm, a former monk of Lérins, is mentioned as Bishop of Nice (1100–07).
Bishops of Nice bore the title of Counts of Drap, making them prince-bishops, since the donation of property situated at Drap, made in 1073 by Pierre, Bishop of Vaison, a native of Nice, to Raymond I, its bishop, and to his successors. Charlemagne, when visiting Cimiez (devastated by the Lombards in 574), caused St. Syagrius to build on its ruins the monastery of St. Pontius, the largest Alpine abbey of the Middle Ages. The diocese was re-established by the Concordat of 1801 as suffragan of Aix. While the Countship of Nice from 1818 to 1860 was part of the Sardinian States, the see became a suffragan of Genoa. When Nice was annexed to France in 1860, certain parts which remained Italian were cut off from it and added to the Diocese of Vintimille. In 1862 the diocese was again a suffragan of Aix. The arrondissement of Grasse was separated from the Diocese of Fréjus in 1886, and given to Nice which since unites the three former diocese of Nice, diocese of Grasse and diocese of Vence.