A speed limit of 20mph will be imposed on all central London roads managed by Transport for London (TfL) in a bid to reduce road deaths.
All TfL roads within the Congestion Charging Zone (CCZ) will be subject to the limit by 2020.
Some critics said the speed limit would make no difference because traffic already moves so slowly in the area.
The Vision Zero scheme is a collaboration between the London mayor, TfL and the Metropolitan Police.
Pedestrians hit by a vehicle driven at 20mph are five times less likely to be killed than if they are hit at 30mph, according to the mayor's office.
A study found that about four lives a year were saved when a 20mph scheme was rolled out in Bristol, but similar plans in Manchester were reviewed over concerns they were not reducing the number of accidents.
London Mayor Sadiq Khan also wants to introduce the 20mph limit on high-risk roads in London's suburbs, but these plans are subject to discussions with borough councils.
He said the "bold and far-reaching plans" will help to reduce the more than 2,000 people who are killed or seriously injured on London's roads each year.
"No death or serious injury on London's roads should be treated as acceptable or inevitable," Mr Khan added.
But Steve McNamara from the Licensed Taxi Drivers Association said the limit will make little difference.
"Most people would love to go as fast as 20mph in the middle of London," he said.
"Average traffic speeds are 6mph in the centre - we have the lowest traffic speed of any city in Europe, barring Moscow.
"I can't think of anywhere in central London it would make any difference at all, at least in the daytime. Those roads are all at a virtual standstill."
TfL-managed roads subject to the new 20mph limit
- Victoria Embankment
- Upper Thames Street Underpass
- Thames Street
- Tower Hill
- Lambeth Bridge
- Albert Embankment
- Blackfriars Road
- The A11 in Aldgate
- The A2 in Borough
Caroline Pidgeon, chair of London Assembly's transport committee, said the announcement was "a start" but that Mr Khan and TfL should be "more ambitious outside the Congestion Zone".
"It's these areas where Londoners should be able to enjoy walking and cycling in safety, so it would be remiss to ignore the roads where the greatest benefits are to be gained."
Other plans in the Vision Zero scheme include new safety standards for Heavy Goods Vehicles and buses, as well as implementing changes at the capital's most dangerous junctions.