A number of new Routemaster designs have been put forward
A company has been chosen to build the new Routemaster bus for London.
Northern Ireland-based vehicle-making company Wrightbus is Transport for London's (TfL) preferred manufacturer
TfL said the first of the "greener" and more accessible, hop-on hop-off, double-deckers could be in service by 2011.
The original Routemasters were phased out from regular service by the end of 2005 as they were inaccessible to wheelchairs or pushchairs.
The bus will have an open platform at one of its three entrances, with the platform able to be closed off at certain times, such as at night.
There will be two staircases and the bus will incorporate the latest hybrid technology to make it 40% more fuel efficient than conventional diesel buses and 15% more fuel efficient than current London hybrid buses.
London Mayor Boris Johnson had promised to bring back a version of the Routemaster, which was first introduced in 1956.
Mr Johnson said: "Londoners have waited with stoic patience as work has continued behind the scenes to select the manufacturer to make the 21st century Routemaster a reality.
"The decision has now been made and we can look forward to a new icon of London that not only returns to the capital the joy of the open platform, but also utilises the latest state-of-the-art green technology, slashing pollution and fuel consumption.
"The countdown is now well and truly on as Wrightbus work 19 to the dozen to deliver Londoners their new bus in 2011, ahead of the world descending on the city for the 2012 Games."
Mark Nodder, managing director of Wrightbus's parent body Wright Group, said: "This project marks the start of an exciting new chapter in passenger transport in one of the world's great cities."
An initial design will be unveiled early next year.