Oberaarhorn, Mountain peak in the Bernese Alps, Switzerland.

Oberaarhorn is a mountain peak in the Bernese Alps reaching 3,631 meters (11,912 feet) that forms a border between the cantons of Valais and Bern. The surrounding landscape is shaped by three major glaciers that flow from different sides of the mountain.

The Oberaarhorn lies on the border between the cantons of Valais and Bern, and its 3,631-metre summit is the tripoint of three glacier basins: the Studergletscher in Valais, and the Finsteraargletscher and Oberaargletscher in Bern. The two source articles record this same division of drainage, with the English text naming the Fiesch and Unteraar basins instead of the Studer and Finsteraar glaciers.

The mountain draws numerous climbers and hikers to its slopes, contributing to the development of mountaineering traditions in the Swiss Alps.

Reaching the summit demands solid mountaineering skills and follows a challenging alpine route classified T4 in difficulty. A mountain hut nearby provides shelter and serves as a key staging point for climbers approaching the peak.

The summit is the tripoint where three glacier basins meet: the Fiesch (or Studer) Glacier on the Valais side, and the Unteraar and Oberaar Glaciers on the Bern side. A climber standing on the 3,631 m top straddles the cantonal border and the watershed between the Rhône and Aare systems.