Transport for London (TfL) will install a 20mph speed limit on all central London roads it manages from next year, following a consultation.
The scheme would see a new limit along 5.5 miles (8.9km) of roads including Millbank, Albert Embankment and Borough High Street by May 2020.
There were nearly 2,000 responses to a public consultation which ran for five weeks until 10 July.
But critics pointed out traffic meant average car speed in London was 6mph.
Steve McNamara, general secretary of the Licensed Taxi Drivers' Association, said: "A 20mph speed limit is pretty academic.
"We support TfL's aim to make London a safer place. However, this can only be done by reducing the excessive number of private hire vehicles on the road."
The plan is part of the mayor of London's Vision Zero scheme, which aims to eliminate all road deaths in the capital by 2041.
The affected roads include all those managed by TfL within the congestion zone, along with the Aldgate Gyratory.
The height of pedestrian crossings will be increased in seven "high-risk" locations, such as on the Embankment and outside Tate Britain.
Of the 1,912 public responses, about half said the plans would lead to more people walking. Some 59% said many more people would choose to cycle.
Nearly 50% of respondents believed the proposals would have no impact on the number of car journeys. Some 58% believed the number business journeys would not be affected.
Penny Rees, of TfL, said: "We know that lower speeds save lives; it's that simple.
"It's clear people agree that making our roads safer will encourage Londoners to travel in more active and sustainable ways."
The Mayor of London, Sadiq Khan, said: "Every single death on London's streets is one too many so I'm really pleased that Londoners have backed our plans."
Roads which would have the new limits are:
- Albert Embankment
- Lambeth Palace Road
- Lambeth Bridge
- Victoria Embankment
- Upper Thames Street
- Lower Thames Street
- Tower Hill
- Aldgate gyratory including: Leman Street, Prescot Street, Mansell Street, Minories and Goodman's Yard
- Borough High Street
- Great Dover Street
- Blackfriars Road
- Part of Druid Street (between Tower Bridge Road and Crucifix Lane)
- Crucifix Lane
- Part of Bermondsey Street (between Crucifix Lane and Tooley Street)
- Part of Queen Elizabeth Street (between Tooley Street and Tower Bridge Road)
Transport bosses have said they also hope to introduce lower speed limits on 93 miles (150km) of streets run by TfL across London over the next five years.
Florence Eshalomi, chair of the London Assembly transport committee, said: "We suggest the Mayor considers going further to areas outside of the Congestion Charge Zone where walking and cycling should be safer.
"Every life lost on the road is tragedy, particularly when the cause is a driver not obeying the speed limit."