The 1977 Irish general election to the 21st Dáil was held on Thursday, 16 June, following the dissolution of the 20th Dáil on 25 May by President Patrick Hillery on the request of Taoiseach Liam Cosgrave. The general election took place in 42 Dáil constituencies throughout Ireland for 148 seats in Dáil Éireann, the house of representatives of the Oireachtas, an increase of four seats with a significant revision of constituencies under the Electoral (Amendment) Act 1974. The election is regarded as a pivotal point in twentieth-century Irish politics. Jack Lynch led Fianna Fáil to a landslide election win, clearly defeating the outgoing Fine Gael–Labour government.

The Taoiseach is the head of government or prime minister of Ireland. The office is appointed by the President of Ireland upon the nomination of Dáil Éireann and the office-holder must retain the support of a majority in the Dáil to remain in office.