US Vice President Joe Biden has signed an executive order to set emissions standards for new power plants, the first such limit issued by a US presidential administration.
It does not apply to existing power plants.
The move will speed the creation of more renewable power from wind and solar, and calls for the mass transport sector to go green as well.
However, the order was criticised by conservative politicians as “the single most expensive regulatory giveaway of our lifetimes”.
Among the biggest winners will be big oil and gas corporations, some of which will be exempt from the stricter rules.
Mr Biden also said the US would stop buying oil from countries that pollute more than they promise to, a move he said would put pressure on others to follow suit.
“The world will be watching to see how others follow,” he said.
Environmental groups have welcomed the directive.
“This is a major moment for US leadership on climate, energy and clean air,” said Tiernan Sittenfeld, director of government affairs at the League of Conservation Voters.