Flåvatn is a lake in the municipalities of Nome and Kviteseid in Telemark county, Norway. The lake is the easternmost of the three connected lakes Bandak, Kviteseidvatnet and Flåvatn, which are all part of the Telemark Canal. The lake's area is 19.52 km2. The outlet is via the river Straumen (Eidselva) which flows down to the lake Norsjø. The village of Kilen lies along the northern shore of the lake and the village of Flåbygd lies at the eastern end of the lake.