Music stars like Metallica and Mariah Carey campaigned for more climate protection and the global fight against poverty at a concert in New York's Central Park.
US President Joe Biden and his wife Jill surprisingly appeared in front of tens of thousands of spectators at the Global Citizen Festival on Saturday evening with a video message.
"We are excited and grateful for the work you are doing and want you to know your fight is our fight," said the First Lady.
The Global Citizen Festival has taken place every year since 2012 during the general debate of the UN General Assembly.
Tickets will be distributed free of charge to Global Citizen supporters.
The leaders of Biden's Congressional Democrats, Chuck Schumer and Nancy Pelosi, both took the stage in person and highlighted the US government's climate package passed in August, which was the largest investment in the fight against global warming in US history is applicable.
However, Barbados Prime Minister Mia Amor Mottley said the island states are still acutely threatened by climate change.
"Yes, my friends, our time is running out," she said.
Women's rights and protests in Iran
Another important topic was women's rights and the protests in Iran following the death of 22-year-old Mahsa Amini after her arrest by the vice squad.
The Iranian-born Berliner Anuscheh Amir-Khalili, who works for refugee women in Germany, said on stage that women worldwide had to flee from abuse, oppression and femicide - "women like Mahsa Jina Amini".
“We have to stand up for oppressed women.
I'm here for you," she told viewers.
EU Commission President Ursula von der Leyen also came on stage in Central Park and said: "We have to take care of our girls and women.
They deserved it."
Global Citizen organized a second concert in Ghana's capital Accra on Saturday, which featured performances by US R&B star Usher and British rapper Stormzy.