Irish nationalism is a nationalist political movement which, in its broadest sense, asserts that the people of Ireland should govern Ireland as a sovereign state. Since the mid-19th century, Irish nationalism has largely taken the form of cultural nationalism based on the principles of national self-determination and popular sovereignty. Irish nationalists during the 18th, 19th, and 20th centuries such as the United Irishmen in the 1790s, Young Irelanders in the 1840s, the Fenian Brotherhood during the 1880s, Fianna Fáil in the 1920s, and Sinn Féin styled themselves in various ways after French left-wing radicalism and republicanism. Irish nationalism celebrates the culture of Ireland, especially the Irish language, literature, music, and sports. It grew more potent during the period in which all of Ireland was part of the United Kingdom, which led to most of the island gaining independence from the UK in 1922.

The United Kingdom of Great Britain and Ireland was a sovereign state in Northwestern Europe that was established by the union in 1801 of the Kingdom of Great Britain and the Kingdom of Ireland. The establishment of the Irish Free State in 1922 led to the remainder later being renamed the United Kingdom of Great Britain and Northern Ireland in 1927.