The American achieved a famous upset win over Muhammad Ali in 1978, in just his eighth professional fight.
He had suffered with health issues in his later years and was diagnosed with advanced stage prostate cancer in 2019.
"His final fight was fought with the same skill, grace and grit that had carried him through so many lifetime challenges," said a statement from his management company.
The former US marine died on Friday evening in Henderson, Nevada, with his wife Brenda Glur Spinks by his side.
