Kassjö is a locality in Umeå Municipality, in Västerbotten County, Sweden. It has 254 inhabitants (2023). The nearest city is Umeå, 17.1 km to the east. Among the landmarks around are Umeå City Church (17.5 km), Västerbottens Museum (17.9 km) and Bildmuseet (18.1 km). Among the natural features are Norrforsen (5.4 km).