Karlovasi is a town, a municipal unit, and a former municipality on the island of Samos, North Aegean, Greece. Since the 2019 local government reform it is part of the municipality West Samos, of which it is a municipal unit and the seat. It is located on the northwest side of the island and it is considered the commercial center of the island. According to the 2021 census, the population of the municipal unit was 10,220 inhabitants. Its land area is 100.330 km2. The municipal unit shares the island of Samos with the municipal units of Vathy, Pythagoreio, and Marathokampos.

Samos is a Greek island in the eastern Aegean Sea, south of Chios, north of Patmos and the Dodecanese archipelago, and off the coast of western Turkey, from which it is separated by the 1.6-kilometre-wide (1.0 mi) Mycale Strait. It is also a separate regional unit of the North Aegean region.