It will be expanded up to the North and Circular roads from October 2021 and will affect large numbers of polluting vehicles that don’t comply with strict emissions standards.
An estimated 100,000 cars, 35,000 vans and 3,000 lorries are to be affected.
Driving non-compliant vehicles within the expanded zone will result in drivers paying a daily ULEZ charge of £12.50.
The ULEZ expansion and tougher rules for emissions are expected to result in more than 100,000 Londoners no longer living in areas exceeding legal air quality limits.
Mr Khan said: “Air pollution is a national health crisis and I refuse to stand back as thousands of Londoners breathe in air so filthy that it shortens our life expectancy, harms our lungs and worsens chronic illness.
“I promised hard-hitting measures to tackle our shameful air pollution and today City Hall is confirming the next stage of our plans to expand the Ultra-Low Emission Zone up to the north and south circular roads.”
He previously confirmed the ULEZ in central London will be delivered in April 2019.