The aid money helps poorer nations deal with the environmental emergency by preventing deforestation and reducing carbon emissions.
Boris Johnson has announced that the sum spent on helping developing countries reduce their carbon emissions will double to more than £11.6 billion.
The prime minister said the increase in the international climate finance pot would come between 2021/22 and 2025/26, as he made a series of commitments to tackle the climate crisis.
The aid money helps poorer nations deal with the environmental emergency by preventing deforestation and reducing carbon emissions, as well as to prepare for the effects of global warming.
The announcement at the United Nations General Assembly in New York on Monday came as the PM launched the Ayrton clean energy fund.
Named after British physicist and suffragette Hertha Ayrton, it will allow scientists to use up to £1 billion of the aid budget inventing new technology to tackle the climate crisis in developing countries.
The PM has put an emphasis on technology's potential to answer the climate emergency and also announced a further £220 million from the overseas aid budget to save endangered species from extinction.
But environmental groups have warned changes to economic policies are essential to thwart environmental disaster, rather than relying on new inventions.
Sam Blewett is the PA political correspondent and is reporting from New York.