Faistenau is a municipality in the Austrian state of Salzburg. It lies in the Flachgau district, the flatland region of the state surrounding the city of Salzburg.
The municipality is made up of several scattered villages and hamlets rather than a single compact town, set in a landscape of meadows, forests and gentle hills at the edge of the Salzkammergut lake country. Its centre, Faistenau village, sits at roughly 800 metres above sea level, with the Osterhorn group of the Salzkammergut mountains rising to the south and east.
Faistenau is best known for the small swimming lakes in its surroundings, above all the Hintersee and the Fuschlsee area nearby, and for the hiking and cross-country skiing routes that pass through the commune. It is a member of the Salzburg Flachgau tourism association and remains largely agricultural, with dairy farming on the surrounding pastures.