Kassjön is a village in Umeå Municipality, in Västerbotten County, Sweden. Kassjön lies at 134 m above sea level. The nearest city is Umeå, 18.2 km to the east. Among the landmarks around are Umeå City Church (18.6 km), Västerbottens Museum (19.0 km) and Bildmuseet (19.1 km). Among the natural features are Norrforsen (6.4 km).