The artists will perform the Keep a Child Alive Black Ball event to present at London's Roundhouse on June 15, which will be hosted by Alicia and Mark Ronson.
In a statement, Alicia, 30, said: 'I've been a fan of George Michael for as long I can remember. He is a legend and an inspiration. His work raising awareness and funds for those suffering with the HIV virus has spanned three decades.
'I'm honoured that George has lent his voice to our KCA cause and I'm so excited that he's singing for us at the Black Ball in London. It is going to be an amazing night!'