The "Faith" hitmaker was close friends with the tragic princess, who died in 1997, and even gave her an advance copy of his 1996 album "Older" so she could provide him with an early review of the songs.
George Michael has been working on a secret track to mark Prince William's marriage to Kate Middleton on 29 April - and he's told fans he knows Diana would have loved it.
In a post on his Twitter.com blog, George Michael writes, "I'm really happy with it... and I know Diana would have approved. She had a copy of 'Older' four months before any of you lot! Diana and my mum. The album's first listeners. They gave me excellent reviews, but then they would have."
The identity of George Michael's new song, which is a cover version of a classic track, is due to be announced on Friday, April 15.