Sadiq Khan is proposing a £3.50 road toll for all drivers with vehicles registered outside of the capital.
The charge would hit anyone crossing the boundary into Greater London - an estimated 1.3m journeys every weekday.
Sadiq Khan urged ministers to 'play fair' in London after the Covid-19 pandemic saw Transport for London's fares income collapse.
Ministers have failed to play fair by Londoners when it comes to financing our world-renowned transport system. It is high time they did so.
The Mayor believes the government should hand over £500m in road tax collected from Londoners every year. The proposed toll is an alternative way of raising the money.
The £3.50 toll would largely apply to motorists who don't have a vote in the mayoral election.
The Mayor's office says that the 'small charge' could have significant benefits in terms of managing congestion, reducing emissions and encouraging more use of sustainable modes of transport.
Traffic levels have returned more quickly to outer London than central London, with levels of traffic in outer London now at around 90 per cent of pre-pandemic levels.
A thorough public consultation process would be required before any charge could be introduced, in addition to economic, environmental and equality impact assessments.
The consultation period would take at least two years.