The fighter was best known for beating Muhammad Ali in 1973, breaking the Hall of Famer's jaw in the process.
Norton, who suffered a stroke last year, ended his brilliant career with a record of 42 wins, seven losses, one draw and 33 knockouts.
He fought in the 1970s era of magnificent heavyweights -- a group that also included Ali, George Foreman, Joe Frazier, Leon Spinks and Jimmy Young.
"They called us handsome. Muhammad they called pretty. But the fairest of them all Ken Norton," Foreman wrote on his Twitter page Wednesday. "What a loss to all of us."
"My heart has been heavy since hearing the news earlier today," boxer Larry Holmes wrote on Twitter. "He was a good man. #RIP #KenNorton."
Norton was born in Jacksonville, Illinois, and was an award-winning athlete in American football and track and field at Jacksonville High School. His prowess on the gridiron earned him a scholarship to Northeast Missouri State University.
He started boxing during his four year-stint in the United States Marine Corps, which he joined in 1963.
He would go on to fight Ali twice more, losing both times. He lost a split decision to Ali later in 1973 and by a unanimous decision in 1976 at Yankee Stadium.
