Some of the city buses are operated by Unibuss, though these are subject to public service obligation contracts with Ruter.

The first tramways in Oslo were created by Kristiania Sporveisselskab (the Green trams) in 1875 when it opened a horsecar line between Stortorvet and Homansbyen.

The municipal A/S Kristiania Sporveier was created in 1924 when the concession for the Blue and Green trams expired.

But it was not until 1993 that the western and eastern networks in the city were connected, and in 2006 the T-bane circle route opened.

The organization structure was largely the brainchild of Peter N. Myhre, former Councilor for Transport of the Progress Party.

A report published by Rokade in January 2011, claimed that the company wasted NOK 55 million per year on unnecessary administration because of the structure.

The report concluded that this also made for unclear lines of responsibility, which could be a safety risk, and that the company could be able to remove 60 administrative positions if it were better organized.