Michael died of apparent heart failure on Christmas Day at his home in Goring, a village on the River Thames in Oxfordshire, west of London, after an award-winning career spanning more than three decades.
Fans placed bouquets of flowers, single roses and emotional messages outside the house, as well as on the pavement in front of his luxurious London home.
"He died so young!" said Karen Walkden, 52, who brought a message to the large red-brick mansion in Highgate in north London.
"It was my generation, it's absolutely shocking," said Walkden, who came from nearby Finchley to the posh neighbourhood adjoining Hampstead Heath.
"Everybody who's been important to me has been ripped away this year -- David Bowie, Victoria Wood," Walkden added, referring to the late rock legend and a much-loved British comedian who both died in 2016.
US funk star Prince and soulful Canadian singer-songwriter Leonard Cohen also passed away this year.
"You have been loved, you were loved, you will be loved. We grew up with you and you spoke for us," read one note outside the Highgate house.
"Shocked and sad... He was a great talent, person and community member," read another note stuck to a yellow bucket containing a plant of small pink roses.
Mags Sorrell, 60, said she had seen Michael in concert around a dozen times.
"On the stage, he looked at his happiest," she said.
Leandros Kalisperas, 39, who said that he like Michael was of a Greek Cypriot background from north London, brought flowers, a candle and a note.
"He shaped my life," he said, wiping away a tear.
"For me there was no one else that can take us to that high, joyous place," said Kalisperas.
'My beloved friend'
Big names in entertainment like Elton John and Madonna hailed Michael's talent and human qualities, while former Wham! bandmate Andrew Ridgeley said he was "heartbroken at the loss of my beloved friend".
Michael was best known for 1980s and 1990s hits like "Freedom", "Careless Whisper", "Faith", "I Want Your Sex" and "Wake Me Up Before You Go Go".
He won a string of awards including two Grammys and three Brits, but run-ins with the law over drugs and a series of bizarre incidents and health scares in his final years often overshadowed his music.
Police said they would be conducting a post-mortem examination and were treating the death as "unexplained but not suspicious".
His manager Michael Lippman told Billboard magazine that the cause of the star's death was heart failure.
Lippman said he was told that Michael had been found "in bed, lying peacefully".
Michael was due to release a documentary about his life and a new album in 2017. His last album "Symphonica" (2014) rose to number one in the charts.
Drug charges, health scares
Michael was born Georgios Kyriacos Panayiotou to a Greek Cypriot father and English mother in north London in 1963.
He met Ridgeley at high school and the pair went on to form Wham! in 1981.
With their good looks, perma-tans, highlighted hair and hedonistic image, the duo captured the go-getting spirit of the age and fast became one of Britain's biggest pop acts.
In 1985, Wham! became the first Western pop band to perform in China as the country was slowly beginning to open up to the outside world.
Following years of speculation over his sexuality, Michael came out as gay in 1998 after being arrested for committing a lewd act in the public toilet of a Los Angeles park.
It was the first of several run-ins with the law.
He notched up police cautions for cannabis and crack cocaine possession and in 2010 was sentenced to eight weeks in jail after crashing his car into a London shop while under the influence of cannabis and prescription medication.
In 2011, he spent several weeks in hospital in Vienna after contracting pneumonia, later saying that he had been close to death.
There were fresh concerns in 2013 when he had to be airlifted to hospital after falling out of his chauffeur-driven Range Rover as it travelled at high speed on a motorway.