Walenstadt is a municipality in the Wahlkreis of Sarganserland in the canton of St. Gallen in Switzerland. It is located on Lake Walen (W "Walenzee" also known as "Lake Walenstadt").

Walenstadt has an area of 17.6 sq mi as of 2006. Of this area, 35.1% is used for agricultural purposes, while 40.4% is forested. Of the rest of the land, 5.3% is settled (buildings or roads) and the remainder (19.2%) is non-productive (rivers or lakes). Until 1952, Walenstadt was known as Wallenstadt.

Lime glacial erratic show that the Seez valley (Seeztal) was 1000 m high covered with ice during the last ice age. As the ice began to melt, wild brooks arise. The south side from the Churfirsten falls almost vertical.

The community Walenstadt is divided in five towns: Walenstadt, Walenstadtberg, Knoblisbühl, Berschis and Tscherlach. In Walenstadtberg is a famous building: The Paxmal, built by Karl Bickel. All towns are linked by a public transport bus system. Walenstadt has a rail station.

Tucked in the eastern corner of Switzerland, Germany and Liechtenstein are just over the mountains and Austria is round the bend to the east.

The Berschis, a prehistoric hill settlement on the St. Georgenberg, and the early medieval chapel of St. Georg on the same hill are listed as Swiss heritage sites of national significance.