Alttoggenburg District () is a former district of the canton of St. Gallen in Switzerland. The district existed from its formation in 1831 until the canton's 14 districts () were reorganized into 8 constituencies () on January 1, 2003. When the district was formed, it was split apart from Untertoggenburg. Today, the area is within the constituency of Toggenburg.
Alttoggenburg contained four communities. Of these, Kirchberg, Lütisburg, and Mosnang remain organized municipalities, while Bütschwil was merged with a neighboring community in 2013 to form Bütschwil-Ganterschwil.