The aim is to urge rich countries to share one billion doses of Covid-19 vaccines with the nations that are struggling most with the pandemic.
Prince Harry welcomed the crowd with the question “are we prepared to do what is necessary to end this pandemic?”
Meghan added: “There is so much that we can do today, now that can get us closer to ending this pandemic and that’s why we’re all here.”
The couple said they have sat with independent global health leaders this week to further understand how to achieve vaccine equality.
“We’re battling more than the virus alone. This is a battle of misinformation, bureaucracy, lack of transparency,” Harry added.
Doors opened for the festival at 2pm with the concert kicking off at 4pm until 10pm.
It is one of seven coordinated concerts across the world in London, Los Angeles, New York City, Paris, Rio de Janeiro, Seoul, Sydney and Lagos as part of a 24-hour broadcast event.
Revellers must be fully vaccinated against coronavirus and show proof of vaccine to enter the outdoor event.
“It was a lovely meeting,” Ms Markle said as they left the UN headquarters.
Ms Mohammed welcomed the commitment and work of the Duke and Duchess on the 17 Sustainable Development Goals, the United Nations said.
The goals were created by the UN in 2015 and tackle issues such as ending hunger and poverty, achieving gender equality and combating climate change.
“The Deputy Secretary-General affirmed support for shared priorities around climate action, women’s economic empowerment, youth engagement and mental wellbeing,” the UN said in a statement.