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 Society of United Irishmen was a sworn association, formed in the wake of the French Revolution, to secure representative government in Ireland. Despairing of constitutional reform, and in defiance both of British Crown forces and of Irish sectarian division, in 1798 the United Irishmen instigated a republican rebellion. Their suppression was a prelude to the abolition of the Irish Parliament in Dublin and to Ireland's incorporation in a United Kingdom with Great Britain.