The Tannhorn is a mountain of the Emmental Alps in Switzerland . It lies to the west of the Brienzer Rothorn and to the east of the Augstmatthorn . On its southern side it overlooks Lake Brienz .

Administratively, the summit is shared by the municipalities of Brienz, to the south and east, Oberried am Brienzersee , to the west, and Flühli , to the north-east. Brienz and Oberried am Brienzersee are in the Canton of Bern , whilst Flühli is in the Canton of Lucerne . The Tannhorn is the southernmost point in the canton of Lucerne.