c. 42) was an act of the Parliament of the United Kingdom which separated the Church of Ireland from the Church of England and disestablished the former, a body that commanded the adherence of a small minority of the population of Ireland (especially outside of Ulster).

The act was passed during the first ministry of William Ewart Gladstone and came into force on 1 January 1871.

Existing clergy of the church received a life annuity in lieu of the revenues to which they were no longer entitled: tithes, rentcharge, ministers' money, stipends and augmentations, and certain marriage and burial fees.

Queen Victoria personally intervened to mediate.

[4] The Irish Church Act was a key move in dismantling the Protestant Ascendancy which had dominated Ireland for the prior century.