The Reformation in Ireland was initiated by King Henry VIII in the 1530s due to his desire for a marriage annulment and subsequent break from Papal authority, leading him to assert royal supremacy over the Church. By 1542, the Irish Parliament, at Henry's command, declared him head of the "Church in Ireland" and elevated the country's status from a Lordship to the Kingdom of Ireland.

However, unlike in England, the Reformation in Ireland was largely imposed by government policy rather than embraced by the public, with the majority of the population staunchly adhering to Catholicism. Its limited success was primarily due to a scarcity of Protestant preachers throughout the 16th century and its perception as an extension of English colonization, prompting strong resistance from both Irish Gaelic and Old English communities. Reforms continued under successors like Edward VI, introducing the Book of Common Prayer from 1549, but the movement largely failed to gain indigenous support, resulting in persistent religious division.