Relatives hurried to his bedside as fans of the singer massed outside the hospital after news of his arrival there emerged, many bursting into tears as his death was announced.
The 50-year-old musical superstar died just as he was preparing for a series of comeback concerts starting July 13 at the 02 arena in London, England.
The performances were seen as the beginning of a public comeback by Jackson, who had spent recent years countering a series of damaging allegations about his private life.
The singer was acquitted in 2005 of charges alleging that he had committed abuses against children and that he had plotted to kidnap a youth who had filed a complaint against him.
Jackson reached the peak of his fame in the 1980s as a solo artist, after leaving his brothers in the already hugely-successful Jackson 5, later known as the Jacksons.
His 1982 album Thriller went on to become the world's then top-selling album of all time, with sales exceeding 41 million copies, cementing his image as the self-styled "king of pop".
But while Jackson's 1987 album Bad was also a strong seller and helped him maintain his position as the biggest solo musical artist in the world, critics and fans alike began to pay increasing attention to dramatic changes in Jackson's physical appearance.
He repeatedly denied reports that he had had plastic surgery to alter his appearance, claiming that a rare skin condition was responsible.
Jackson stated preference for the company of children and his friendship with a chimp also earned him critics and the nickname "Wacko Jacko".
He leaves behind three children, two he had with Debbie Rowe, whom he divorced in 1999, and another from a mystery surrogate mother.
He sparked controversy in 2002 when he playfully dangled his then-infant son, Prince Michael II, over a hotel balcony in Berlin while a throng of fans watched from below.
He was also previously married to Lisa Marie Presley, daughter of legendary singer Elvis Presley, but they divorced in 1996.