Sarnen (Swiss Standard German pronunciation: [ˈzarnən] ) is a small historic town, a municipality, and the capital of the canton of Obwalden situated on the northern shores of Lake Sarnen (German: Sarnersee) in Switzerland. It has a population of just over 10,000 and is surrounded by countryside and mountains. Sarnen is located 20 km south of Lucerne.

The official language of Sarnen is (the Swiss variety of Standard) German, but the main spoken language is the local variant of the Alemannic Swiss German dialect.

Stone Age and Bronze Age finds show that the Sarnen valley was inhabited from the earliest times. Over the years Sarnen developed into an important trading center.