Sadiq Khan has told a US audience that it is "important to take people with you" if you want to reduce air pollution and tackle climate change.
London's mayor made the comments at the beginning of a four-day trip to New York.
He said he had gained permission to bring in bold policies once Londoners had been "educated" on the environmental and health crisis.
But his visit has been criticised by the Conservative mayoral candidate.
Susan Hall said: "While Sadiq Khan enjoys the perks, swanning off to America to lecture everyone about his Ulez (Ultra Low Emission Zone) tax, Londoners are paying the price.
"The poorest have been hit hardest by his disastrous Ulez expansion, facing debts or a £12.50 daily charge."
Mr Khan is in New York as part of his role as the chair of the C40, a network of mayors from nearly 100 global cities which shares ideas and expertise on climate change as part of the city's Climate Week. The organisation is funding his visit.
The trip comes just three weeks after the expansion of Ulez to the whole of London.
Speaking at an event on Sunday, the mayor said politicians needed to be "better story-tellers".
"If we get things wrong, if we have policies that are unpopular, we'll be voted out," he said.
He said the scheme had reduced toxic air by nearly half in the centre of London and a further 20% in inner London.
Mr Khan was referring to a City Hall study from earlier this year which suggested these were reductions in pollutants which went beyond what would have happened if Ulez had not been introduced.
The mayor said he had faced obstacles including hostility "from a vocal minority drowning out a silent majority", but said he had Londoners on his side.
"In London we spent some time educating people about the consequences of air pollution that are linked to climate change.
"Once they were aware it wasn't just an environmental but a health crisis, we had permission to bring in bold policies.
"That's why it's important to take people with you."
Since the announcement was made about the expansion in 2022, it has been met with opposition by some politicians and motorists, while five Conservative councils took the policy to the High Court.
They lost after the judge ruled the mayor's expansion decision "was within his powers".
The mayor is due to lead a private session of the group on Tuesday, where he may be asked by fellow mayors about the criticisms and political difficulties he has faced back home.
He is booked to appear on several US TV shows today before attending a UN climate change summit on Wednesday.
Mr Khan told Sunday's event that these cities representing more than 700 million people and a quarter of the world's GDP (Gross Domestic Product) were ahead of national governments in finding solutions.
He said: "We've had enough of governments meeting every year, a lot of talk, a lot of wasted energy. Why not get cities and indigenous people and civic society involved and help us bring about change?"
The mayor will also go to a ceremony for the Earthshot prize attended by Prince William, and meet US businesses looking to invest in London.