爱尔兰王国 (爱尔兰语：Ríocht na hÉireann；英语：Kingdom of Ireland)是指爱尔兰国会在1541年通过《爱尔兰王位法》后在爱尔兰岛上成形，和英格兰王国有共主邦联关系的国家，借此取代1171年以来爱尔兰领地 (Lordship of Ireland)的建制，而时任爱尔兰领主的亨利八世则成为1169年来首位爱尔兰国王。但英格兰人对爱尔兰统治基于早前的武力征服，王国的统治也并非没有挑战。而法理上独立的爱尔兰王国，国祚直至1801年爱尔兰和大不列颠王国合并组成大不列颠及爱尔兰联合王国为止。

The Kingdom of Ireland (Classical Irish: Ríoghacht Éireann; Modern Irish: Ríocht Éireann) was a client state of the Kingdom of England that existed on Ireland from 1542 until 1800. It came into being when the Parliament of Ireland passed the Crown of Ireland Act 1542 and proclaimed King Henry VIII of England as King of Ireland. The territory of the Kingdom had previously had the status of a lordship of the crown. The Parliament of Ireland passed the Acts of Union 1800 by which it abolished itself and the Kingdom. The act was also passed by the Parliament of Great Britain. The act also had the effect of establishing the United Kingdom of Great Britain and Ireland on the first day of 1801 by uniting the crowns of Ireland and of Great Britain. In its early years, the Kingdom of Ireland had limited recognition. While some Protestant powers in Europe recognised Henry and his heir Edward as monarch of Ireland, no Catholic power did so. Henry's daughter, Queen Mary I of England, was recognised as Queen of Ireland by Pope Paul IV in 1555.