Sigmundsherberg is a municipality in the district of Horn, in the Austrian state of Lower Austria. It lies in the Waldviertel region of the country, in the northeastern part of Austria.
The municipality is made up of several small villages and settlements rather than a single large town, which is typical of the rural communities in this part of Lower Austria. Its administrative seat and main settlement shares the name Sigmundsherberg.
Like much of the surrounding district of Horn, the area is predominantly agricultural and rural, characterized by rolling countryside and a low population density. It is connected to the regional road and rail network that links the smaller communities of the Waldviertel with larger towns in the region.