The Diocese of Luçon is a Latin Church diocese of the Catholic Church in France. Its see is Luçon Cathedral in the commune of Luçon. The diocese comprises the department of Vendée. Created in 1317 out of the diocese of Poitiers, its existence was interrupted during the French Revolution, but it was restored in 1821, along with the Bourbon restoration.

Jean de Lorraine was the third son of the ruling Duke of Lorraine, and a French cardinal, who was archbishop of Reims (1532–1538), Lyon (1537–1539), and Narbonne (1524–1550), bishop of Metz, and Administrator of the dioceses of Toul, Verdun, Thérouanne, Luçon, Albi, Valence, Nantes and Agen (1538–1550). He was a personal friend, companion, and advisor of King Francis I of France. Jean de Lorraine was the richest prelate in the reign of Francis I, as well as the most flagrant pluralist. He is one of several cardinals known as the Cardinal de Lorraine.