Au is a town in the Bregenz Forest in the Austrian state of Vorarlberg. It lies in the westernmost part of Austria, in the Alpine region of the Bregenz Forest (Bregenzerwald).
The town is one of the communities of the Bregenz Forest, a rural and mountainous area of Vorarlberg known for its Alpine landscape and its distinctive local culture and architecture. Au shares in this setting as a small settlement within the region.