Dún Laoghaire was once part of the borough of Dún Laoghaire, and remains the only town in Ireland to have its own Vocational Education Committee. It is considered part of the Greater Dublin Area.
The town had been officially renamed Kingstown in 1821 in honour of a visit by King George IV, but reverted to its ancient Irish name by resolution of the town council in 1921, one year before Irish independence. The name derives from its founder, Laoghaire, a 5th-century High King of Ireland, who chose the site as a sea base from which to carry out raids on Britain and France. 'Dún' is an Irish word meaning 'fort'. King Laoghaire is famous for having allowed Saint Patrick to travel the country and preach Christianity.
Dún Laoghaire was hit by a stray German bomb during World War II, the bomb landing near the Peoples Park at Rosmeen Gardens. Damage from the bomb was limited to buildings.