This extension involved the construction of a new rail tunnel from Selnau to Hbf, and a new underground intermediate station adjacent to the former terminus.

The underground platform and tracks used at Hbf were already in existence, having been built prior to 1973 for a U-Bahn scheme that was ultimately rejected by voters.

At the same time passenger services were withdrawn between Sihlwald and Sihlbrugg, although the track still exists and is used by occasional trains.

At Adliswil, a short walk provides an interchange to the Adliswil-Felsenegg cable car, which rises to the summit of Felsenegg.

Standard Zürcher Verkehrsverbund (ZVV) zonal fare tariffs apply to the line.

[3][13] The night service (SN4) of the S4 line, operating on weekends after midnight, runs between Zürich Hauptbahnhof and Langnau-Gattikon.

The Zürcher Museums-Bahn (ZMB) operates occasional heritage railway services over the Sihltal line.

[16] Passenger services on the Sihltal line are operated with a mixture of single and double deck cars, sometimes with examples of both types in the same train.

[17] As of 2019[update], service continues to be provided by Class 450 and 456 [de] electric locomotives in push-pull operation, with 3–4 single- and double-decker coaches.