City Hall hopes to introduce the additional emissions surcharge from October next year.
The plans were put out for formal consultation on Monday.
Mr Khan is also putting forward plans to extend the capital’s ultra low emissions zone to the north and south circular roads.
Under the proposals, the owners of diesel and petrol vehicles manufactured before or up to 2005 that do not meet Euro 4 emissions standards for nitrogen oxide (NO2) and particulates will be required to pay £10 on top of the congestion charge.
The mayor has also called on the government to put in place a national diesel scrappage scheme to help people replace vehicles affected by his plans.
City Hall said its research showed people living in London’s most deprived communities, often by busy roads, are on average exposed to 25% higher levels of harmful NO2 pollution.
It is estimated that the equivalent of 9,400 premature deaths occur each year in London due to illnesses caused by long-term exposure to air pollution and 448 schools in London are in areas exceeding legal air quality levels.
Diesel vehicles are recognised as a major contributor to pollution and associated health impacts in London and the mayor wants to phase out these vehicles from the bus, taxi and other fleets.
Mr Khan said: “Toxic air in London is a health emergency that requires bold action, including introducing charges for older polluting vehicles and expanding the ultra low emissions zone.
“I am determined to help every Londoner breathe cleaner air. After the massive response to my first consultation I now need the public to let me know their views on my detailed proposals to help clean-up our filthy air.”