St Patrick's Cathedral, Armagh is a Church of Ireland cathedral in Armagh, Northern Ireland. It is the seat of the Anglican Archbishop of Armagh and Diocese of Armagh. The origins of the site are as a 5th century Irish stone monastery, said to have been founded by St. Patrick. Throughout the Middle Ages, the cathedral was the seat of the Catholic Archbishop of Armagh, head of the Catholic Church in Ireland, and one of the most important churches in Gaelic Ireland. With the 16th-century Protestant Reformation, the Irish Church divided between Protestants and Roman Catholics, with the cathedral being retained by the Church of Ireland.

The Church of Ireland is a Christian church in Ireland, and an autonomous province of the Anglican Communion. It is organised on an all-Ireland basis and is the second-largest Christian church on the island after the Roman Catholic Church. Like other Anglican churches, it has retained elements of pre-Reformation practice, notably its episcopal polity, while rejecting the primacy of the pope.