There is a comprehensive public transport system in Oslo, consisting of buses, trams, trains, metro (T-bane) and boats. The public transport is planned and coordinated by Ruter

Ruter Service Center (formerly known as Trafikanten is the information centre for public transport in Oslo. It is situated at Jernbanetorget, just outside Oslo Central Station, by the foot of the clock tower, as well as at Aker Brygge and at Oslo Airport (Gardermoen). They hand out free maps, give information and sell all kinds of tickets. The Ruter website has timetables, maps, route planner and search engines for all city transport in Oslo, as well as all transport in the nearby counties of Akershus, Østfold, Oppland, Hedmark, Buskerud, Vestfold and Telemark. The Oslo Tourist Information Centre is in the same office at Jernbanetorget, at the rear counters.

There are two main hubs for public transport inside the city centre: Oslo Central Station (Oslo S) / Jernbanetorget and Nationaltheateret (underground). All metro lines pass these stations, all trains pass Oslo S and most trains (including the Airport Express Train (Flytoget)) pass Nationaltheateret. Nationaltheateret is most convenient for key buildings such as the Royal Palace, the National Gallery, the Parliament, Oslo Concert Hall and Oslo City Hall.