The 53-year-old star passed away at his home in Goring-on-Thames, Oxfordshire, South East England, on Christmas Day (25.12.16) and his manager Michael Lippman has confirmed the cause of death.
He told Billboard that he received a call telling him that Michael had been found "in bed, lying peacefully" and that there was "no foul play whatsoever". He added that Michael's death from heart failure was unexpected.
A statement from Thames Valley Police read: "Thames Valley Police were called to a property in Goring-on-Thames shortly before 2pm Christmas Day. Sadly, a 53-year-old man was confirmed deceased at the scene. At this stage the death is being treated as unexplained but not suspicious. A post mortem will be undertaken in due course. There will be no further updates from Thames Valley Police until the post mortem has taken place."
George's publicist announced his death in a statement around 11pm on Christmas Day, saying: "It is with great sadness that we can confirm our beloved son, brother and friend George passed away peacefully at home over the Christmas period. The family would ask that their privacy be respected at this difficult and emotional time. There will be no further comment at this stage."
George – who had battled alcohol and drug issues in his life – began his career as one half of duo Wham! with Andrew Ridgeley best known for hits such as 'Club Tropicana', 'Careless Whisper' and festive classic 'Last Christmas'.
The singer – real name Georgios Kyriacos Panayiotou – then went on to become one of the world's biggest solo stars in a career that spanned across four decades.
After George's death was revealed, tributes poured in, with a heartbroken Andrew taking to Twitter to remember his late bandmate. He wrote: "Heartbroken at the loss of my beloved friend Yog. Me, his loved ones, his friends, the world of music, the world at large. 4ever loved. A xx (sic)."
Elton John took to Instagram to remember the star, writing: "I am in deep shock. I have lost a beloved friend – the kindest, most generous soul and a brilliant artist. My heart goes out to his family, friends and all of his fans. @GeorgeMichael #RIP (sic).
And Queen guitarist Brian May expressed his deep shock, posting a picture of George on Instagram and writing: "No words. RIP George. Bri
George previously had a major health scare in late 2011 when he contracted pneumonia but after being treated at a Vienna hospital he made a recovery but later admitted it had been "touch and go" whether he lived.