The cause of death was not disclosed.
He tested positive for HIV in 1996 before a fight with Arthur Weathers. Morrison said the following week that he had contracted the virus due to a "permissive, fast, and reckless lifestyle," but later insisted the diagnosis was a false positive and even challenged the existence of the virus.
Nicknamed "The Duke" on disputed claims that he was the grandnephew of John Wayne, Morrison was born in Gravette, Ark. on Jan. 2, 1969 and grew up in Oklahoma. Born to a family of boxers, he began fighting at the age of 10 and entered fights at the age of 13 by using a fake ID.
Morrison turned professional in 1998, scoring a first-round knockout of William Muhammad in New York City en route to beginning his career 19-0, scoring 15 knockouts.
He earned his first title bout in 1991, suffering his first professional defeat by fifth-round knockout to undefeated Ray Mercer. Morrison bounced back to win six consecutive fights in 1992 and two more in 1993, earning another shot at the heavyweight title with a knockout of Carl "The Truth" Williams.
That set up Morrison's bout with Foreman in Las Vegas on June 7, 1993. Morrison avoided trading big blows with Foreman, who was staging a comeback, and scored a unanimous decision in a 12-round fight with the WBO champion.
The stage appeared to be set for a fight with WBC champion Lennox Lewis when Morrison suffered a stunning first-round knockout at the hands of Michael Bentt - getting knocked down three times in a fight televised on HBO.
Morrison would fight nine times over the next two years. He scored a dramatic victory over Razor Ruddock by sixth-round TKO after being knocked to his knees in the first round and recovering to force a standing count in round two.
The Morrison-Lewis bout took place later in 1995, with Lewis earning a sixth-round knockout.
Morrison was scheduled to fight Weathers on Feb. 10, 1996, in Las Vegas when the positive HIV test was discovered less than an hour before the bout. The fight was immediately postponed without a reason being given at the time.
Five days later, Morrison held a news conference in which he said he contracted HIV due to a "permissive, fast, and reckless lifestyle" and announced his boxing career was over. However, by Sept. 19, 1996, Morrison announced he wanted one final fight, although he was unable to line up an opponent.
In 2006, Morrison attempted to make a comeback, saying his HIV diagnosis was the result of a false positive. The Nevada commission stood by its test results and declined to approve Morrison to fight in the state. He passed medical tests in Arizona, however, and beat John Castle in West Virginia in February 2007.
The New York Times reported Morrison tested negative for HIV three times in 2007, including one specifically for the newspaper. Three experts reviewed the case and concluded the 1996 result had indeed been the result of a false positive, although ringside doctors said the negative results were not based on Morrison's blood.
Morrison was scheduled to fight in Quebec in 2011, but declined to take a pre-fight test because he claimed it was the same kind of test he was administered in 1996. He offered to take a public tests, but the Quebec commission did not attend.
Morrison retired from the ring with a career record of 48-3-1 with 42 knockouts.
ESPN reported last month that Morrison was critically ill and had been bed-ridden for more than a year.