Glarus Süd is a municipality in the Swiss Canton of Glarus . It comprises the upper Linth valley, and the entire Sernf valley, and includes the villages of Betschwanden , Braunwald, Diesbach, Elm, Engi, Haslen, Hätzingen , Leuggelbach , Linthal, Luchsingen , Matt, Mitlödi , Nidfurn , Rüti, Schwanden, Schwändi and Sool.

Glarus Süd is one of three municipalities of the canton of Glarus, the others being Glarus and Glarus Nord .

The municipality of Glarus Süd was created on 1 January 2011, incorporating the former municipalities of Betschwanden, Braunwald, Elm, Engi, Haslen, Linthal, Luchsingen, Matt, Mitlödi, Rüti, Schwanden, Schwändi and Sool. At the time of its creation, Glarus Süd was the largest Swiss municipality by area. As of 1 January 2015, it was overtaken in size by the expanded municipality of Scuol in the canton of Graubünden.