The Irish Army or Irish establishment, in practice called the monarch's "army in Ireland" or "army of Ireland", was the standing army of the Kingdom of Ireland, a client state of England and subsequently of Great Britain. It existed from the early 1660s until merged into the British Army in 1801, and for much of the period was the largest force available to the British monarchy, being substantially larger than the English and Scottish establishments.

The Kingdom of Ireland was a monarchy on the island of Ireland that was a client state of England and then of Great Britain. It existed from 1542 to the end of 1800. It was ruled by the monarchs of England and then of Great Britain, and was administered from Dublin Castle by a viceroy appointed by the English king: the Lord Deputy of Ireland. Aside from brief periods, the state was dominated by the Protestant English minority. The Protestant Church of Ireland was the state church. The Parliament of Ireland was composed of Anglo-Irish nobles. From 1661, the administration controlled an Irish army. Although styled a kingdom, for most of its history it was, de facto, an English dependency. This status was enshrined in Poynings' Law and in the Declaratory Act of 1719.