Barbara Ann Beach Boys
Singles and album chart success have followed his death earlier this week
Wham's Last Christmas reached number 7 in the singles chart - the first time the festive hit has appeared in the top ten for 31 years.
Martin Talbot, from the Official Charts Company, said: "The sudden and terribly sad death of George Michael has naturally prompted his fans to re-explore his rich catalogue again, paying tribute to his incredible talent, both as a solo artist and founder of Wham!.
"Quite appropriately, given the season, it is Last Christmas which makes the biggest impact."
One of the singer's most famous songs, Careless Whisper, sits just outside the top 40, while Don't Let The Sun Go Down On Me - his duet with Elton John - is at 91.
Meanwhile in the album chart, George Michael's greatest hits collection, Ladies and Gentleman, reached the top ten for the first time in 17 years.
Combined sales and streaming helped Ladies and Gentlemen surge by 5,625% in the week to Friday.
Five other of Michael's albums also broke into the top 100, including Faith, Older, Symphonica and his last Wham! album, The Final.
The charts have been released just 5 days after George Michael died at his home in Goring-On-Thames, Oxfordshire.
The 53-year-old was found by his partner Fadi Fawaz, hours before a planned Christmas lunch.