Helsinki Regional Transport Authority
| Native name | Helsingin seudun liikenne (Finnish) Helsingforsregionens trafik (Swedish) | 
|---|---|
| Company type | Kuntayhtymä (Inter-municipal cooperation) | 
| Predecessor | YTV HKL | 
| Founded | 1 January 2010 | 
| Headquarters | Opastinsilta 6 A, Helsinki, Finland | 
| Area served | Greater Helsinki | 
| Key people | Suvi Rihtniemi (CEO) | 
| Services | Public transport | 
| Members | City of Helsinki City of Espoo City of Vantaa City of Kauniainen City of Kerava Municipality of Kirkkonummi Municipality of Sipoo Municipality of Tuusula Municipality of Siuntio | 
| Number of employees | c. 400 | 
| Website | www | 
The Helsinki Regional Transport Authority (Finnish: Helsingin seudun liikenne, HSL; Swedish: Helsingforsregionens trafik, HRT) is the inter-municipal authority that maintains the public transportation network of the nine municipalities of Greater Helsinki, Finland.
HSL oversees the operation of all of Helsinki's public transportation. The system consists of local buses, trams, metro trains, ferries, commuter trains, and bikeshare.
Apart from four electric buses, HSL does not own rolling stock. Due to this, HSL relies on third-party contractors for the day-to-day operation of the transit system.