Adshel, the roadside arm of Clear Channel, has retained the £250 million, ten-year Transport for London advertising contract for the capital's bus shelters.
Adshel had held the previous bus-shelter contract since 1980. It retained the account following a pitch process that included the rival street-furniture companies JCDecaux, Maiden/Cemusa and Viacom.
The new contract will cover ad sales as well as maintenance and design across half of TfL's 5,000 bus shelters.
The remaining 250,000 shelters were not put up for pitch and will remain under Adshel's jurisdiction.
Adshel now plans to overhaul London's bus shelters and has presented TfL with a series of new designs, including one by the renowned architect Richard Rogers. It has also devised several technological options, such as digital journey planners, CCTV and customer help points.
Julie France, the group managing director of Clear Channel UK, told Campaign that Adshel intended to increase the number of panels available to advertisers.
"London is the crown jewels of any advertising campaign. However, compared with other British and European cities, it is underdeveloped, particularly in terms of six-sheet posters," she said.
"We are looking at ways to develop the number of panels in premium locations. However, this will be done sensitively - we are not going to flood the market."
The pitch lasted nearly a year - the tenders were released last July.
Adshel will implement its planned alterations to the capital's bus shelters early next year.
France added: "This rewards the successful relationship Adshel has had with TfL over the past 25 years. We understand the role shelter infrastructure plays in shaping a world-class city's image for tourists and residents."