Gosau is situated along the Gosaubach stream in the Salzkammergut region. The center of the town is at an elevation of 767 (2,516'). 58.9% of the municipality is forested.
At the southern end of Gosau there is a road leading to the Vorderer Gosausee, a lake with a scenic view of the Dachstein.
Gosau is one of the few Lutheran communities in Austria with about 71% of the population being Lutheran.