Eigersund is a municipality in Rogaland county, Norway. Egersund landdisstrikt (rural district) was established as a municipality on 1 January 1838 (see formannskapsdistrikt). Augne was separated from Eigersund in 1839. Helleland and the town of Egersund were merged with Eigersund on 1 January 1965.
Eigersund extends from the North Sea coast to the border of Vest-Agder. It borders Hå in the north, Sokndal in the south. The municipality is centered on the town Egersund, and includes the island Eigerøya. The landscape includes a lot of rivers and seas, as well as woods. The town itself is mostly industrial. The lakes Eiavatnet and Teksevatnet lie in the municipality.
The Old Norse form of the name was Eikundarsund. The first element is the genitive case of the name of the island Eikund (now Eigerøya) and the last element is Sund which means "strait" or "sound". The first element in the name of the island is eik which means "oak" and the last element is the suffix -und which means "plentiful of" (i.e. "the island covered with oak trees").