The Kingdom of Ireland (Irish: Ríoghacht Éireann) refers to the country of Ireland in the period between the proclamation of Henry VIII as King of Ireland by the Crown of Ireland Act 1542 and the Act of Union in 1800.

It replaces the Lordship of Ireland, which had been created in 1171.

King Henry VIII is recognized as monarch of Ireland by some Protestant powers in Europe, although not by the Catholic monarchies in Europe.

However his daughter Mary I is recognized as Queen of Ireland by the pope in 1555.

The separate Kingdom of Ireland ceases to exist when Ireland joins with the Kingdom of Great Britain to form the United Kingdom of Great Britain and Ireland in 1801.