Sadiq Khan's Ultra Low Emission Zone has raked in an eye-watering £224million.
A third of the nine-figure total raised last year was brought in through penalty charge notices.
The remainder of cash was raised through daily charge payments.
Transport for London has claimed the cash brought in by Ulez has been spent on "set up costs" as City Hall prepares for the scheme's expansion in August.
It also has spent some of the money on "running and improving" the rest of the network.
A Freedom of Information request found Ulez generated £224,633,003 in 2022.
An average of £18.7million was raised every month, the BBC's request has revealed.
Motorists driving through the current zone are forced to cough up a £12.50 daily charge if their vehicle meets Khan's Ulez standards.
However, drivers who do not pay the fee will receive a penalty charge of £180.
The fine can be reduced to £90 if paid within a fortnight.
City Hall launched Ulez in April 2019 when it was brought in to cover the same area of the existing congestion zone.
Motorists across the entirety of Greater London will face the charge from August following the imminent expansion.
Khan's plans have been considered extremely controversial, particularly amongst Conservative Party Assembly Members.
A High Court Judge last month announced that five Tory-led councils could challenge Khan's expansion.
Conservative contenders for the 2024 London Mayoral Election have also vowed to scrap the expansion.
Former Northern Ireland Secretary Theresa Villiers, who represents constituents in Chipping Barnet, is pushing to allow ministers to intervene on decisions made by the London Mayor about transport and air quality.