The singer, 50, was pronounced dead soon after he arrived at an LA hospital.
The LA Coroner has confirmed his death.
Lieutenant Fred Corral told CNN Jackson was pronounced dead at 2:26pm (7.26am) local time after reportedly suffering a cardiac arrest, but not a heart attack.
“I can tell you at this time that we were notified by West Los Angeles Police Department detectives that Mr Jackson was transported … to the hospital, and upon admitting, he was unresponsive and was pronounced dead at approximately 2:26 this afternoon,” Corral told CNN.
Corral said an autopsy would “most likely” be carried out tomorrow but would not speculate on the exact cause of death.
“Everything is still ongoing. We will be responding to the hospital to move Mr Jackson to our facility where he will be examined to determine the cause of death,” Corral said.
“At that point, as I said, there’s no further medical history until we get and review the medical records.”
Jackson, who had been preparing for his comeback tour, was rushed to the UCLA Medical Centre shortly before 12.30pm local time.
Special Section: Michael Jackson dead at 50
Paramedics received a 911 call directing them to the Bel Air home, off Sunset Boulevard, which Jackson rented for $100,000 a month.
Fire Department Captain Steve Ruda told US media Jackson was not breathing when they arrived. Mr Ruda said they received him at about 12.21pm.
When they arrived, they performed CPR and rushed Jackson to the medical centre, about a six-minute drive away.
Brian Oxman, a Jackson family attorney, said he was told by brother Randy Jackson that Michael Jackson had collapsed at his home in west Los Angeles.
Family members were told of the situation and were either at the hospital or en route, Oxman said.
His sister La Toya was seen rushing to the medical centre in tears.
The Los Angeles Times and CBS reported that Jackson arrived in a deep coma and was pronounced dead soon afterwards.
His dad Joe Jackson was shocked and confused after learning his son had been hospitalised.
Gallery: Michael Jackson and his very Wacko life that turned tragic
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“His mother is on her way to the hospital now,” Joe Jackson said.
Police officers cordoned off the road outside Jackson’s Bel Air home yesterday as fans swamped the UCLA Medical Centre.
Michael is survived by three children _ Michael Joseph Jackson, Jr, Paris Michael Katherine Jackson and Prince “Blanket” Michael Jackson II.
The seventh of nine children, Jackson was born in Indiana before moving to LA with his family where he became the star of the Jackson 5.
Watch the unfolding scene live at the hospital where Michael Jackson died
The artist behind the biggest-selling album of all time, Thriller, Jackson was attempting a comeback after years of headlines about his child molestation charges (he was acquitted) to his plastic surgery and his habit of wearing face masks.
He had been scheduled to perform 50 sell-out concerts at London’s 02 arena from next week to March 2010.
Jackson started in the music business at the age of 11 as a member of the Jackson 5 with his brothers.
The group had a number of hits on Motown in the 1970s.
Five of his solo albums are some of the top-selling albums of all time: “Off the Wall,” 1982’s “Thriller,” “Bad,” “Dangerous” and “HISstory.”
He was twice inducted into the Rock and Roll Hall of Fame, and had 13 Grammy awards and 13 number one singles.
He has sold over 750 million albums worldwide.
His total earnings have been estimated at $500 million dollars. His music videos on MTV, such as “Beat It,” “Billie Jean” and “Thriller” were some of the most influential early music videos, and his sound influenced numerous hip hop and R&B artists.
He was tried and acquitted of sexual abuse allegations in 2005.
He married nurse Deborah Jeanne Rowe in Sydney, with whom he fathered a son, Michael Joseph Jackson, Jr, also known as Prince, and a daughter, Paris Michael Katherine Jackson.
After they divorced in 1999, he retained full custody of the children.
In the early 1990s, he was briefly married to Lisa Marie Presley, the daughter of Elvis Presley.
He lived at Neverland Ranch in Santa Barbara from 1988 to 2005.
It was sold to Colony Capital, although he still owns a stake in the property.
To celebrate his 50th birthday, Sony BMG released a compilation album, “King of Pop,” in various countries, but it was not released in the US.
The Los Angeles Times reported Jackson’s condition had died after going into a deep coma.
In recent months, Jackson had been trying to revive his flagging career which crashed after he faced child-sex charges – allegations he eventually beat in court.
As the first step in this comeback, the singer had been due to play 50 sell-out shows at London’s O2 Arena starting in July.
But the King of Pop had already postponed the first few nights’ shows amid claims he was suffering health problems.
The Daily Mail in London reported organisers AEG Live said this was in order to make sure everything for the “massive and technically complex show” was running smoothly.
But critics say ongoing concerns about Jackson’s health were the real reason behind the gigs having to be postponed.
Earlier this year, Jackson was seen emerging from a doctors three times in one week amid rumours that he was battling skin cancer.
The claims were denied by his representatives.
Jackson has not been on tour for more than a decade, but the concerts at the O2 were seen as his final comeback before finally retiring from music.
In later years, Jackson – whose personal life and sexual preferences remained somewhat mysterious – was plagued by child-sex allegations.
He was accused of molesting an American boy Jordan Chandler after befriending his father early in the 1990s and reportedly settled for $US30million for the allegations to go away and avoid possible charges.
But in 2003, Jackson faced new child-sex allegations that he abused a teenage boy he had also befriended during sleepovers. The singer ended up facing seven sex charges in court but was acquitted.
The paedophile image, however, did enormous damage to his career and Jackson became a virtual recluse, with his behaviour increasingly weird and reports that his financial position was becoming dire due to bad investments, skyrocketing legal bills and a public turned against him.