Altach is a municipality in the district of Feldkirch, in the westernmost Austrian state of Vorarlberg.

Five other municipalities surround Altach: Hohenems in the district of Dornbirn, Götzis and Mäder in the district of Feldkirch, and Oberriet and Diepoldsau in the Swiss canton St. Gallen.

The Habsburgs ruled over the villages in Vorarlberg alternately from Tyrol and Further Austria.

Altach has been part of the Austrian state of Vorarlberg since the latter's founding in 1861.

As of the season 2021-22, the football club SC Rheindorf Altach plays in Bundesliga, the highest division.