Utah Valley Regional Medical Center spokeswoman Janet Frank says life support was terminated and Coleman died at 12:05 p.m.
Coleman was hospitalized Wednesday after falling and suffering a head injury at his home south of Salt Lake City, according to family members.
For a while, it seemed that Gary Coleman's cherubic face was everywhere, from TV to T-shirts to lunchboxes.
On Diff'rent Strokes, he played precocious Arnold Jackson, who, with his brother Willis (Todd Bridges), was adopted by a wealthy, white Manhattan man (Conrad Bain) and his daughter (Dana Plato).
Coleman's pudgy cheeks and flawless comic timing made him the break-out star of the popular series, which ran from 1978-86.
His signature line, "Whatchoo talkin' 'bout, Willis?" became a national catchphrase.
But Coleman's bright beginnings were overshadowed by domestic disputes, legal troubles and health issues. Coleman was born with a congenital kidney disease that resulted in his small stature. He had two kidney transplants and required frequent dialysis.
At the height of Diff'rent Strokes' popularity, Coleman reportedly received up to $100,000 an episode. Beginning in 1980, he won four consecutive People's Choice Awards as Favorite Young TV Performer
He parlayed his prime-time success into steady work in TV guest spots, made-for-TV movies and feature films, including On the Right Track and The Kid with the Broken Halo. The latter inspired the animated TV series The Gary Coleman Show.
But in the years after Diff'rent Strokes, Coleman was in the headlines more often for his off-screen troubles than for his acting.
In 1989, he successfully sued his parents and former advisers for misappropriation of his trust fund, which had dwindled. He was awarded $1.3 million.
In 1999, Coleman filed for bankruptcy, blaming his troubles on financial mismanagement.
In 1998, while working as a security guard, he was charged with assault for hitting a woman who had been seeking an autograph. He pleaded no contest and received a suspended sentence.
In 2007 he was cited for disorderly conduct after arguing with his wife, Shannon Price, whom he married that August. They had met on the set of the 2006 comedy Church Ball.
In 2008, he and Price appeared on the syndicated TV show Divorce Court in an attempt to save their marriage.
But last year, the two were involved in a domestic dispute which resulted in Price being arrested and both receiving disorderly conduct citations.
And he recently settled a lawsuit with a man he allegedly hit with his car outside a Utah bowling alley in 2008.
In January, Coleman was arrested for failure to appear in court for an unspecified earlier charge.
Coleman's troubles led him to be the butt of jokes for comedians and he even inspired a character by the same name in the Tony-winning musical Avenue Q.
Through it all, Coleman maintained his perspective and sense of humor. "I parody myself every chance I get," he said. "I try to make fun of myself and let people know that I'm a human being, and these things that have happened to me are real. I'm not just some cartoon who exists and suddenly doesn't exist."
Despite his real-life travails, Coleman will remain an '80s TV icon, a quick-witted boy whose onscreen charm lives on in television syndication.