Herøy is a municipality in Møre og Romsdal county, Norway. It is part of the Sunnmøre region. The administrative centre is the town of Fosnavåg on the island of Bergsøya. The industrial area of EggesbøNes is located south of Fosnavåg on the same island. The Runde Environmental Centre is located in the northern part of the municipality on Runde island.
Herøy was established as a municipality on 1 January 1838 (see formannskapsdistrikt). On 1 January 1867, the sub-parish of Sande was separated from Herøy to form a municipality of its own. This left Herøy with 1,999 residents. On 1 January 1873, an area of Sande (population: 362) was transferred back to Herøy. On 1 January 1889, the Eiksund area and Ekø island (population: 119) were transferred from Sande to Herøy.
The municipality (originally the parish) is named after a archipelago of small islands (Old Norse: Herøyjar). The first element is herr which means "army" (here in the sense skipaherr which means "military fleet") and the last element is the plural form of øy which means "island". Before 1918, the name was written Herø.