The London congestion charge zone is to be extended to include Kensington and Chelsea, the Mayor has announced.
From February 2007, motorists will have to pay £8 on weekdays when crossing the new boundary in west London.
Critics say extending the zone will push traffic into Hammersmith and Fulham and could kill off local trade.
Ken Livingstone also announced that from September 2006 drivers could pay the current central London charge the day after travelling in the zone.
Currently drivers must pay in advance or on the day of travelling.
When the Chelsea and Kensington extension comes into effect, charging hours will end 30 minutes earlier at 6pm.
A Transport for London survey showed 63% of residents and 72% of firms were opposed to the western extension.
Liberal Democrat London Assembly transport spokesman Geoff Pope said the extension decision "flew in the face of common sense" and was "the wrong scheme at the wrong time".
Referring to London's falling retail figures, London Chamber of Commerce press and public affairs director Dan Bridgett said: "This is a bad decision at the worst possible time".
He added that the message that most companies opposed the extension had been "received, understood and blatantly ignored".
But the Mayor said the extension would reduce traffic in the zone by up to 22%, shaving five minutes off a typical journey time.
"Extending the existing zone will bring considerable benefits to this area of London," he said.
'Mayor not persuaded'
He said he did not dismiss residents' and companies' concerns out of hand but that he was not persuaded that representations outweighed arguments in favour of the extension.
He added he was well aware only 24% of the public responses to the consultation on the extension supported the proposal but he was satisfied there had been genuine consultation.
He also said he felt objectors had had a proper opportunity to voice their concerns and it was not necessary to hold an inquiry into the extension scheme.
In April, about 100 vehicles held a go-slow protest over extension plans.
At the time Gordon Taylor, chairman of the West London Residents' Association, said there was anger over the extension.
Campaigners said the extension was unfair, saying only 5% of the roads covered in the extended zone suffer congestion.
Businesses in the area spoke of fears of falling trade when the charge comes into force.
The central area of London has been subject to a congestion charge for vehicles since February 2003. It went up from £5 to £8 a day in July this year.