Whithorn Priory is a ruined Scottish monastery that also served as a cathedral, located in Whithorn, Dumfries and Galloway.
Fergus, the Lord of Galloway founded the priory in the middle of the 12th century, during the reign of King David I of Scotland. Originally, Augustinian Canons founded a community here but were then replaced in 1175 by Premonstratensian canons, known as the White Canons.
The canons of Whithorn formed the cathedral chapter of the Diocese of Galloway, as the old succession of bishops died out in the 8th or 9th centuries. The prior stood next in rank to the bishop, as can be seen from the order of signatories to an episcopal charter early in the 13th century, the community enjoyed the right of electing the bishop, although this was occasionally overruled in favour of the secular clergy by the Archbishop of York.
Whithorn was a place of pilgrimage, due to its connection with Saint Ninian. Many Scottish sovereigns, among them Margaret (queen of James III), James IV, and James V, made repeated pilgrimages to the saint's shrine, leaving rich offerings. Due to this, the monastery thrived, until the dissolution under the Scottish Reformation. The priory was put under the rule of a commendatory prior in 1516. The last Catholic prior, Malcolm Fleming, was imprisoned in 1563 for the crime of saying Mass.
The monastery lands continued to belong to the bishopric until the Revolution of 1688. The priory church, which served also as the cathedral of the diocese, had a long nave without aisles, a choir of about the same length and a lady chapel beyond. Thomas Sydserf, Bishop of Galloway 1635–8, undertook the remodelling of the nave.
In 1684, the nave and western tower were still intact, but the existing remains consist only of the roofless nave and the extensive vaulted crypts constructed under the eastern end of the church. The cathedral was excavated, then restoration works carried out in 1886, by William Galloway at the expense of John Crichton-Stuart, 3rd Marquess of Bute.
The complex is now a scheduled monument.