The former Labour MP, who had previously committed to a target of 2050, said he wanted to make the capital the “greenest city in the world”.
Announcing his “green new deal”, Mr Khan said he would also focus on improving air quality and access to green space in London. The moniker echoes similar proposals in the US by Democratic congresswoman Alexandria Ocasio-Cortez.
“There is no doubt that this is an ambitious target and it is going to be hard for our city to meet, but unless London is stretched we will never make the changes we need,” Mr Khan said in a speech to the Fabian Society’s new year conference.
He added: “We are at a critical moment in history – our planet is burning, towns across our country are flooding and thousands of Londoners are dying prematurely because of our filthy air.
“Our capital needs a mayor who will ensure it is fit for future generations and work to make London the greenest city in the world.”
Mr Khan said City Hall would implement tougher environmental standards, move away from fossil fuels and reduce waste.
Several other UK cities have also set a similar 2030 target, including Leeds and Glasgow, while Nottingham wants to become the country’s first ever carbon neutral city in 2028.
Across Europe, three Nordic cities including Copenhagen, Oslo and Stockholm have committed to becoming carbon-neutral, or fossil-fuel-free, by between 2025 and 2030.
However Mr Khan’s pledge immediately attracted criticism from campaigners who object to the controversial £1bn project to build a new road tunnel under the Thames.
“You can’t be carbon neutral by 2030 without sharp reductions in emissions from surface transport,” the Stop The Silvertown Tunnel Coalition group said on Twitter.
“Which means massively reducing private car trips. Which means there’s no case at all for the Silvertown Tunnel. And you’ll need to invest that £1bn in public transport and cycling.”
Mr Khan claimed his green policies would be a “dividing line” between his campaign and his Conservative rival Shaun Bailey, who has focussed on tackling crime in the capital.
He accused Mr Bailey of “shamefully seeking to defend his government’s failure to meet its climate and air pollution obligations and delay taking the action we need”.
Mr Bailey responded by telling The Independent that the government “has some of the most ambitious climate policy in the world“.
He added: “Londoners shouldn’t be fooled by the Mayor’s empty promises. The Mayor has failed to do almost everything he promised on the environment, including planting trees and improving our bus fleet, which would have helped to clean our air. In fact, his only success is implementing Boris Johnson’s ULEZ.”
Labour activists passed a commitment at their autumn party conference to work towards zero carbon emissions by 2030. The party softened its pledge during last month’s election due to pressure from trade unions and the impact it would have on jobs.
Additional reporting by agencies