The Theodulhorn (French: Mont de Saint-Théodule[2] - 3,469 m) is a mountain of the Pennine Alps, overlooking the Theodul Pass on the border between Switzerland and Italy.

It lies south of Zermatt (in Valais) and east of Breuil-Cervinia (in the Aosta Valley).

The northern side of the mountain is heavily glaciated and is part of a ski area.

The Theodulhorn is the easternmost summit of the range descending from the south-east ridge of Matterhorn, named Furgggrat.

It is named for Theodul Pass, which is in turn named for Saint Theodul, patron saint of the Valais.