Lomnessjøen is a lake in Rendalen Municipality in Innlandet county, Norway. The villages Åkre and Otnes are located on the shores of the lake. The lake is part of the Renaelva river system. The Renaelva river flows into the lake from the north. The south end of the river drains into the larger lake Storsjøen which is about to the south of this lake.
