Utah Valley Regional Medical Center spokeswoman Janet Frank said the actor’s life support machine was switched off and he died at 18.05 GMT.
Coleman became a star after Diff’rent Strokes debuted in 1978. He played younger brother Arnold Jackson in a pair of African-American siblings adopted by a wealthy white man.
His popularity faded when the show ended after six seasons on the NBC network and two on ABC.
Coleman suffered continuing ill-health from the kidney disease which stunted his growth and also had a host of legal problems in recent years.
He suffered the haemorrhage at his Santaquin home, 90km south of Salt Lake City, on Wednesday.
A statement from the family said he was conscious and lucid until midday on Thursday, when he slipped into unconsciousness.
Diff’rent Strokes drew most of its laughs from the tiny, 10-year-old Coleman.
Race and class relations became topics on the show as much as the typical trials of growing up.
Coleman as young Arnold was an immediate star, and his sceptical “Whatchu talkin’ ‘bout?” — usually aimed at his brother, Willis — became a catchphrase.
In a 1979 Los Angeles Times profile, his mother, Edmonia Sue Coleman, said her son had always been a ham as a small child. He acted in some commercials before he was signed by TAT, the production company which created Diff’rent Strokes.
The series lived on after it left television thanks to DVDs and YouTube.
But its equally enduring legacy became the former child stars’ troubles in adulthood, including the 1999 suicide of Dana Plato, who played the boys’ white, teenage sister Kimberly.
Todd Bridges, who played Coleman’s brother, was tried and acquitted of attempted murder.
Coleman had financial and legal problems in addition to continuing ill-health from the kidney disease which required dialysis and at least two transplants. As an adult, his height reached only 4ft 8in (1.42m).
In 1989, when Coleman was 21, his mother filed a court request trying to gain control of her son’s $6 million fortune, saying he was incapable of handling his affairs. He said the move “obviously stems from her frustration at not being able to control my life”.
In a 1993 television interview, he said he had twice tried to kill himself by overdosing on pills.
He moved to Utah in autumn 2005 and, according to a tally in early 2010, officers were called to assist or intervene with Coleman more than 20 times in the following years. They included a call where Coleman said he had taken dozens of Oxycontin pills and “wanted to die”.
Some of the disputes involved his wife, Shannon Price, whom he met on the set of the 2006 comedy Church Ball and married in 2007.