The expansion of ultra-low emission zone (ULEZ) to outer London boroughs has been ruled as lawful by the High Court.
Five Conservative-run councils had launched legal action back in February over the expansion.
The scheme will come into force from 29 August and see the drivers of the most polluting vehicles charged £12.50 a day to use them.
The hope of those behind the plan is it will incentivise people to use cleaner transport alternatives and, as a result, help improve the city’s air quality.
And TfL has claimed only a small number of people will be impacted, with nine out of 10 vehicles compliant with ULEZ requirements.
But the councils challenged the roll-out in the courts, saying the capital’s Labour mayor, Sadiq Khan, had exceeded his legal powers with such a large expansion of the scheme.
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Khan stands by his ULEZ expansion
The four local authorities – Hillingdon, Bexley, Bromley and Harrow in London, plus Surrey County Council – also claimed the consultation on the plan was flawed, and not enough information had been shared over the scrappage scheme, which provides pay-outs to people prepared to ditch their vehicles.
While other parts of the challenge were dismissed in April, the councils were granted a hearing in the High Court, and the two sides fought it out over two days of evidence.
The ruling comes a week after the debate around ULEZ dominated a local by-election and the fall-out from the results.
The seat of Uxbridge and South Ruislip – left vacant by the departure of Boris Johnson – seemed ripe for the taking for Labour in light of recent polling that gives the party a double digit lead over the Tories.
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Starmer: “ULEZ was the reason that we lost the by-election in Uxbridge.”
But the Conservative candidate managed a narrow victory – albeit seeing the majority for the party fall from over 7,000 to less than 500 – having turned its campaign into a referendum on ULEZ.
Since then, Labour have been in turmoil over the policy and whether to support it, with Sir Keir Starmer saying he had asked the mayor to “reflect” on the impact of the scheme.
However, Mr Khan has said he is committed to ULEZ expansion, telling Sky News: “It was a difficult decision to take. But just like nobody will accept drinking dirty water, why accept dirty air?”
Following the ruling, a source close to the mayor said: “Good news today but the mayor always said this was a really tough decision, he is always listening to Londoners and any questions they have and continues to listen to concerns so the expansion can be implemented as fairly as possible.
“It is a really important policy because air pollution is impacting Londoners. The scrappage scheme is being expanded next week, so every small business in London will be eligible for £5,000 if they have a non compliant van, and £2,000 for cars and all families on child benefit, a big change that will make the transition as easy as possible.”