"What better place to play? There are few better causes in the world than the cause of freedom," he said.
Former president and international statesman Mr Mandela will be the guest of honour at the South Africa Freedom Day Concert in Trafalgar Square on Sunday.
The unique charity event will see performers as diverse as jazz trumpeter and political activist Hugh Masekela playing alongside pop band Atomic Kitten and US rock giants REM.
"I don't know if it is his sort of thing or not, but I think the atmosphere tomorrow is going to be great and he is going to appreciate it," he said.
Mr Mandela is expected to watch the show from the balcony of South Africa House which for many years was the scene of round-the-clock anti-apartheid protests.
REM bass player Mike Mills said Trafalgar Square was a "beautiful" location.
"What better place to play? There are few better causes in the world than the cause of freedom," he said.
Mills said he would be playing for a close friend who grew up in South Africa but now lives in Britain.
The band's lead guitarist Peter Buck, 44, spoke little and refused to comment on a recent alleged air rage incident.
Publicity-shy Buck faces a string of charges related to the incident on 21 April and has been bailed to reappear at Uxbridge Magistrates Court on 18 June.
Artists perform free
REM are considered one of the most influential rock bands of the last two decades and have notched up more than 35 million album sales.
In Sunday's mixed line-up they will share the stage with Ladysmith Black Mambazo, The Corrs, Mel B, and, amongst others, a group of 36 musicians from South Africa and Britain.
Peter O'Connor, 25, who plays the djembe, a South African drum, said he was thrilled to be performing on the same stage as some of his musical idols.
The musician from Connahsquay, North Wales, said: "It is unbelievable to think we will be playing with REM and Atomic Kitten. I'm hoping to meet them."
All the artists are performing for free in aid of the Nelson Mandela Children's Fund and The Prince's Trust.
Organisers said the 20,000 allocated tickets had been snapped up and anyone without one should not come to the square on Sunday.