Karmøy is a municipality in Rogaland county, Norway. It is southwest of the city of Haugesund in the traditional district of Haugaland. The administrative centre of the municipality is the town of Kopervik.
Most of the municipality lies on the island of Karmøy. The island is connected to the mainland by the Karmøy Tunnel and the Karmsund Bridge. It is known for its industries, as well as for fishing. Karmøy is also well known in Norway for its beautiful heather moors and the white sand surfing beaches.
The 230 km2 municipality is the 315th largest by area out of the 422 municipalities in Norway. Karmøy is the 21st most populous municipality in Norway with a population of 42,229, making it one of the largest in the region. The municipality's population density is 192.4 PD/km2 and its population has increased by 10.1% over the last decade.