Kamala Harris speaks during the Tripling Renewable Energy and Doubling Energy Efficiency by 2030 session at the COP28 in Dubai on Saturday. Agence France-Presse
"Today, we are demonstrating through action how the world can and must meet this crisis," Harris told the climate summit in Dubai.
The new money, which must be approved by the US Congress, will go into the Green Climate Fund (GCF), which was created in 2010.
The last US contribution to the fund for developing countries was made under then President Barack Obama, who committed $3 billion in 2014.
US President Joe Biden sent Harris in his place to COP28.
The world's biggest climate fund funnels grants and loans for adaptation and mitigation projects in developing countries, such as solar panels in Pakistan or flood management in Haiti.
Prior to the US announcement, $13.5 billion had been pledged to the GCF.
Agence France-Presse