The former South African president is scheduled to attend an outdoor concert in his honor in Hyde Park on Friday.
Performers include Queen, Annie Lennox, Leona Lewis and the Soweto Gospel Choir. Ailing diva Amy Winehouse is also scheduled to sing, if her doctors allow it.
Proceeds from the concert will go to the 46664 fund, the AIDS charity named for the number Mandela wore while imprisoned by South Africa's apartheid authorities.
Mandela also is due to meet prominent officials and supporters, including British Prime Minister Gordon Brown, former U.S. president Bill Clinton and U.S. talk show host Oprah Winfrey.
Mandela, who turns 90 on July 18, has visited London many times, and has expressed gratitude to the city for the constant vigil that was held outside the South African Embassy during the apartheid years.