The speech, as part of Nelson Mandela Day, will see the Duke of Sussex speak in front of an informal General Assembly gathering.
A UN spokesman told DailyMail.com: ‘The South African Mission has confirmed the participation of the Duke and the Duchess at Monday’s commemoration.’
His speech may refer to the impact of climate change and world hunger, reports say.
This year’s Nelson Mandela Day tagline is: ‘Do what you can, with what you have, where you are.’
The duo are said to have been keen to honor Mandela since visiting his widow Graça Machel in 2019.
Machel said to the couple at the time: ‘It’s wonderful meeting you. I’m sure we’re going to be working together in the future. I can feel the vibe.’
Prince Harry’s mother, Princess Diana, famously met with Mandela in Cape Town in March 1997, just five months before her tragic death.
The couple appeared at the last UN General Assembly in September 2021. During that visit, the couple didn’t participate in the speeches in the assembly hall.
It would be the first public appearance since last month’s Queen’s Platinum Jubilee celebrations. The couple kept a low profile at the event.