The Peerage of Ireland consists of those titles of nobility created by the English monarchs in their capacity as Lord or King of Ireland, or later by monarchs of the United Kingdom of Great Britain and Ireland. It is one of the five divisions of Peerages in the United Kingdom. The creation of such titles came to an end in the 19th century. The ranks of the Irish peerage are duke, marquess, earl, viscount and baron. As of 2016, there were 135 titles in the Peerage of Ireland extant: two dukedoms, ten marquessates, 43 earldoms, 28 viscountcies, and 52 baronies. However, these titles have no official recognition in the Republic of Ireland, with Article 40.2 of the Constitution of Ireland forbidding the state conferring titles of nobility and stating that an Irish citizen may not accept titles of nobility or honour except with the prior approval of the Irish government.

Peerages in the United Kingdom form a legal system comprising both hereditary and lifetime titles, composed of various ranks, and within the framework of the Constitution of the United Kingdom form a constituent part of the legislative process and the British honours system. The British monarch is considered the fount of honour and is notionally the only person who can grant peerages, though there are many conventions about how this power is used, especially at the request of the British government. The term peerage can be used both collectively to refer to the entire body of titled nobility, and individually to refer to a specific title. British peerage title holders are termed peers of the Realm.