An Irish nationalist is generally one who seeks (greater) independence of Ireland from Great Britain, including since 1921 the goal of a United Ireland. The nationalist position is often contrasted with that of Unionists.

In the 19th century most "nationalists" were in favour of Home Rule – an Irish parliament within the United Kingdom. Following the defeat of Charles Stewart Parnell and the Gaelic Revival, physical force republicanism became increasingly important and, after the Easter Rising of 1916, became the dominant force in Irish nationalism.

In Northern Ireland today the term is used to refer either to the Catholic population in general or specifically the supporters of the moderate Social Democratic and Labour Party led by Mark Durkan, with the more radical members of the Catholic community being labelled republicans. Originally, however, the term republican was applied to those who advocated the complete independence of Ireland from Great Britain while nationalist denoted those satisfied with the Home Rule arrangement that arose from the Irish Civil War of the early 1920s and was further codified by the Statute of Westminster in 1931.

The parties widely recognized as representing nationalist and republican politics today include Fianna Fáil, Sinn Féin, and the SDLP.