Lemonsjøen is a lake in Vågå Municipality in Innlandet county, Norway. It is located on the eastern edge of the Jotunheimen mountain range. The 3.6-square-kilometre (1.4 sq mi) lake lies about 10 kilometres (6.2 mi) south of the village of Vågåmo. The larger lake Tesse lies about 5 kilometres (3.1 mi) west of this lake and the lake Flatningen lies about 4 kilometres (2.5 mi) to the northeast.

• List of lakes in Norway