Its line included the St. Gallen–Wattwil section of the St. Gallen–Wattwil–Rapperswil project, which was promoted by the engineer "Lusser" and for which a concession was granted on 27 June 1890.

As a result of the skilful tactics of the canton of St. Gallen, construction of the line was transferred to the Toggenburgerbahn, the builder of the Wil–Ebnat-Kappel railway.

However, it did not have to start construction, as its nationalisation was imminent and it was taken over by the United Swiss Railways (Vereinigte Schweizerbahnen; VSB).

After a railway accident in the Ricken Tunnel on 4 October 1926, in which 9 people died, the immediate electrification of the line was approved.

The line branches off in Uznach from the Rapperswil–Ziegelbrücke railway, which was opened between Rüti and Glarus by the VSB on 15 February 1856.