The Diocese of Sion is a Latin Catholic ecclesiastical territory in the canton of Valais, Switzerland. It is the oldest bishopric in the country and one of the oldest north of the Alps. The history of the Bishops of Sion, of the Abbey of St. Maurice of Valais as a whole are inextricably intertwined.

The Republic of the Seven Tithings was a state in what is now the Swiss canton of Valais during the early modern period, and an associate of the Old Swiss Confederacy.