Duncan "suffered a myocardial infarction on July 13 and never fully recovered," a written statement from Joy Fehily said.
Clarke died at a Los Angeles hospital where he had been since having the heart attack more than seven weeks ago.
According to TMZ, it was Duncan's girlfriend Omarosa Manigault-Stallworth, a reality star and former contestant on "The Apprentice," who had acted quickly and provided lifesaving efforts when he had the heart attack.
Most recently he was on the TV series, "The Finder," on the Fox network.
His co-star Mercedes Masohn tweeted: "Today is a sad day. Michael Clark Duncan passed away this morning. Known for his moving performance in The Green Mile. RIP MCD. You'll b missed."
According to Entertainment Weekly, the TV series was canceled in May.
A towering and hulking figure, the 6-foot-5-inch Duncan also was known for his deep voice.
In 1998, he landed his first significant movie part, playing Bear in the film "Armageddon," where a crew of drillers from a oil rig save the Earth from an asteroid.
A year later he was in the "The Green Mile" as John Coffey, a role that landed him an Academy Award nomination for best supporting actor.