Onsjö is a village in Halmstad Municipality, in Halland County, Sweden. Onsjö lies at 44 m above sea level. The nearest city is Halmstad, 6.6 km to the east. Beaches nearby: Frösakull (2.2 km), Tylösand (3.7 km), Tjuvahålans (4.8 km). Among the landmarks around are St. Nicholas Church (6.6 km), Söndrums kyrka (3.1 km) and Vapnö Church (5.2 km).