Ausserbinn is a former municipality of the canton of Valais , Switzerland , and now part of the municipality of Ernen . Prior to its incorporation within Ernen, it was one of Switzerland's smallest municipalities with a population of only 47 as of 2000.

The village covers a total area of 4.5 km² and ranges in elevation from 1100 m to 2500 m on the mountain of Eggerhorn. The centre lies at 1300 m above sea level. Ausserbinn is situated in the Binn Valley, well known for its abundant flora and minerals.

A Postbus route connects Ausserbinn to the railway station at Fiesch .