It was reported that he was rushed in an ambulance to a hospital in Los Angeles after he suffered a cardiac arrest at his home.
When paramedics arrived Michael had no pulse and they were unable to revive him.
However, there was no official confirmation of the reported death and spokespersons for Michael could not be reached for comment.
His passing will be mourned by millions of his fans around the world and a huge blow, especially those who had managed to get tickets to watch his much-anticipated concert - his curtain call, as he termed it – in the UK scheduled for next month.
Michael hadn't performed any major concerts since 2001.
Aljazeera has the story below.
Pop singer Michael Jackson has died after suffering a heart attack, a US website has said.
Paramedics were unable to revive Jackson after receiving a call to his home in Los Angeles on Thursday, TMZ.com, a celebrity news website, said.
"We've just learned Michael Jackson has died ... Michael suffered a cardiac arrest earlier this afternoon and paramedics were unable to revive him," TMZ reported.
"We're told when paramedics arrived Jackson had no pulse and they never got a pulse back," the report said.
There was no official confirmation of the reported death and spokespersons for Jackson could not be reached for comment.
A spokesman for the Los Angeles Fire Department had earlier told The Los Angeles Times that paramedics responded to a call from an address corresponding to Jackson's at 12.21pm (2021 GMT).
Officials at the UCLA hospital, where Jackson is believed to have been taken, were not immediately available for comment. - Al Jazeera
Farewell Michael. May you rest in peace.
Also read here Reports: Legendary 'King of Pop' Michael Jackson, 50, has died and here Michael Jackson pronounced dead.