The Brienzer Rothorn is a mountain of the Emmental Alps, in Switzerland. With an elevation of 2,350 metres above sea level, the Brienzer Rothorn is the highest summit of the range. To its west lies the Tannhorn, whilst to its east are Arnihaaggen, Höch Gumme and the Brünig Pass (1,008 m). On its south side it overlooks Lake Brienz, whilst to the north it looks out over the Waldemme valley.
Administratively, the summit is shared by the municipalities of Brienz, to the south-west, Schwanden bei Brienz, to the south-east, Giswil to the north-east, and Flühli, to the north-west. Brienz and Schwanden bei Brienz are in the canton of Bern, Giswil is in the canton of Obwalden, and Flühli is in the canton of Lucerne. The Brienzer Rothorn is the highest point in the canton of Lucerne.
The summit can be reached from Brienz by the Brienz Rothorn Bahn (steam train), the summit station being located at 2,244 metres on the Bernese side. It can also be reached from Sörenberg, in Flühli, by a cable car.