It was built as part of the route from Rüti to Glarus, which was opened by the United Swiss Railways (German: Vereinigte Schweizerbahnen, VSB) on 15 February 1859.

The line was built as an extension of the Wallisellen–Uster–Rapperswil railway (Glatthalbahn), which had been extended from Wetzikon to Rüti on 15 August 1858 after its acquisition by the VSB.

The route between Rapperswil and Uznach was electrified in connection with a train accident in the Ricken tunnel on the Uznach–Wattwil railway on 4 October 1926 that led to the death nine people as a result of suffocation from carbon monoxide poisoning.

With the timetable change on 10 December 2023, the new double-track was officially opened, which allowed for more frequented traffic between Rapperswil and Uznach (four trains per hour and direction).

These were replaced in the late 1980s and early 1990s by Neuer Pendelzug (new push-pull trains, NPZ) RBDe 4/4 sets, which are nicknamed "Hummingbirds" because of their colourful paintwork.

The rolling stock now consists only of NPZ "Domino 3" push-pull trains, which are coupled in the rush hour to form 6-car sets.