The Sofia trolleybus system () forms part of the public transport network of Sofia, the capital city of Bulgaria. Trolleybuses first began serving Sofia on 8 February 1941, on a route to the suburb of Gorna Banya, but that initial system closed on 9 September 1944. The current system opened only four years later, on 1 May 1948.
The system presently comprises ten routes with network build, of which are currently in use.
As of 2020, the average speed of the trolleybus system in Sofia is 15.7 km/h.
Trolleybus transport was the last form of surface public transport to develop in Sofia, after buses and trams. The first Sofia trolleybus line opened on 8 February 1941, in what was then the Kingdom of Bulgaria. It was more than long, and connected the city with the Gorna Banya quarter. The line was covered by 2 MAN trolleybuses, which were stored on the last stops during the night, due to the lack of depot. It closed on 9 September 1944.
The city's second trolleybus system, the first part of the current system, opened on 1 May 1948, by which time the country had become the People's Republic of Bulgaria. In the 1950s and 1960s, massive development of the trolleybus transport in Sofia began. At that time, the construction of new trolleybus routes proceeded especially rapidly, and two depots ("Stochna Gara" and "Nadezhda") were opened, with a total capacity of 160 trolleybuses. In 1951, the first Bulgarian made trolleybuses entered service.
In 1987, a new depot, "Iskar", was opened with a capacity of 130 trolleybuses. Levski depot was opened in 1994 with capacity of 60 trolleybuses. As of 2021 three depots are in operation: Nadezhda, Iskar and Levski. The latter also serves as a storage and overhaul facility.
As of October 2025, the following trolleybus lines in Sofia are in service:
As of January 2026, the Sofia trolleybus fleet consisted of 139 trolleybuses, of which around 115 are operational.
The following models are currently part of the fleet:
The heritage fleet consists of the following vehicles: