Vehicles which do not meet European emissions standards and enter the zone which will be subject to a £12.50, a charge which will apply 24 hours a day, for every day of the year.
They will also have to pay the £11.50 congestion charge, which applies between 7am and 6pm on weekdays.
Vehicles which meet the European emissions standards will not be penalised but these are likely to be newer models.
Transport for London (TfL) said the charge will be enforced “on the declared emissions of the vehicle rather than the age”.
But a TfL spokesperson added that petrol cars which meet ULEZ standards will generally be those registered with the DVLA after 2005, while diesel cars will have been registered after September 2015.
The ULEZ will expand to an inner London area bounded by the North and South Circular roads from 25 October 2021.
If a driver fails to pay the charge within a fortnight, they will be fined £160. The fine will be halved if paid within two weeks of being issued.
Sadiq Khan, the mayor of London, described air pollution in the city as “a shameful health crisis, and an issue of social justice”.
“Air pollution has the biggest impact on the poorest Londoners who own the fewest cars,” Mr Khan said.
It is thought that the zone will cover around 40,000 cars a day, as well as 19,000 vans, 2,000 HGVs and 700 coaches.
Drivers of heavier load vehicles, such as buses and lorries, which do not meet European standards face a £100 daily charge under the new rules.
Some modes of transport, including black cabs, private hire vehicle, will be exempt from the charge.
Residents in central London and drivers registered with a “disabled” or “disabled passenger vehicles” tax class will also be exempt from the charge until 2021 and 2025 respectively.
The ULEZ was announced in 2014 by former London mayor Boris Johnson. It was later brought forward from 2020 to 2019 by Sadiq Khan.
However, there has been some concern the charge will hit poorer drivers especially hard.