'Hurricane' Boxer Who Inspired Hollywood Dies
Longtime friend and caregiver John Artis said Carter, who had prostate cancer, died in his sleep on Sunday.
Carter spent 19 years in prison after being wrongfully convicted of murdering three white men in Paterson, New Jersey, in 1966.
He was convicted alongside Mr Artis in 1967 and again in a new trial in 1976, largely on the testimony of two thieves who later recanted their stories.
Carter was freed in 1985 after years of appeals and public advocacy.
His ordeal became an international symbol of racial injustice, motivating Bob Dylan's song Hurricane in 1975.
Denzel Washington received an Academy Award nomination for his portrayal of the boxer-turned-prisoner in 1999.
Carter's convictions abruptly ended his boxing career.
The undersized middleweight went 27-12-1 in his career with 19 knockouts, but never held a title belt.
His most memorable win came when he stopped two-division champ Emile Griffith in the first round in 1963.
He also fought for a middleweight title in December 1964, losing a unanimous decision to Joey Giardello.
A network of friends and volunteers, including boxing legend Muhammad Ali, called for Carter's release from prison.
In an interview on PBS in 2011, Carter said: "I wouldn't give up. No matter that they sentenced me to three life terms in prison.
"I wouldn't give up. Just because a jury of 12 misinformed people ... found me guilty did not make me guilty. And because I was not guilty, I refused to act like a guilty person."
After his release, Carter moved to Toronto, where he served as the executive director of the Association in Defence of the Wrongly Convicted from 1993 to 2005.
He continued to advocate for prisoners he believed to be wrongfully convicted until his death.