As of 2021[update], the system consists of six lines and a total route length of 54.0 km (33.6 mi).

Initially, trolleybus lines were created on new routings intended to complement, rather than compete with, the city's existing tram network.

This company had been founded in 1927 as Kraftwagenbetrieb der Städtischen Strassenbahn Zürich ("Motor Vehicle Operator of the Zurich Municipal Tramway") and had been renamed in 1935.

During that period, vehicle replacement on that line was carried out using a so-called Bügelwagen ("current collector") on tram tracks.

[4] Line 33 was extended from Toblerplatz to Bahnhof Tiefenbrunnen in November 1998, bringing into use a newly constructed section of overhead wires.

An overhead wire crossing at that point, Affoltern, was not approved on safety grounds, due to the high 15 kV AC voltage of the railway line.

Within the boundaries of the central workshop in Altstetten, there is a special trolleybus test route.

They were made by Saurer, Tüscher, FBW and SWS, carried fleet nos.

The VBZ's subsequent procurement of series production FBW vehicles between 1959 and 1964 included fleet nos.

Its second series of articulated vehicles, delivered in 1974/1975, consisted of fleet numbers 70–100, and was also manufactured by FBW.

The first low-floor trolleybus to operate in Zurich, it was tested on the system between October 1997 and March 1999.

Earlier, at the start of 2006, there had been extensive test runs using a bi-articulated vehicles from the Geneva trolleybus system.

For 2012, the Verkehrsbetriebe Zürich plans to replace all remaining high-floor vehicles with an additional 21 articulated Swisstrolley 3 and 17 bi-articulated Hess lighTrams.

[13] The associated increase in the system's capacity, combined with a thinning of service frequencies, should enable the reduction of the fleet by five units.

[15] Work is underway to make bus routes 69 (Milchbuck – ETH Hönggerberg) and 80 (Triemlispital – Bahnhof Oerlikon) electrified by 2024 and 2025, respectively.