Tyson, the youngest of three children, was born into a poor African-American family in Brooklyn, New York. His father never was a significant part of his life, and both his parents died before he was 21.
By the age of ten he was already in trouble with the police for burglary and robbery, and spent part of his childhood living on the streets, out of parental control. When he was 12 he was sent to the Tryon School for Boys, a juvenile offenders institution, for purse snatching. While there he was discovered by the boxing trainer, Gus D'Amato (who died in 1985). He was released into D'Amato's guardianship the next year and according to some sources he was legally adopted by him and/or D'Amato's sister-in-law, Camille Ewald.
He won the World Boxing Federation and International Boxing Federation world heavyweight title in 1987 but lost it in 1990 to James Douglas.
In 1992 he was imprisoned for six years for the 1991 rape of a beauty-contest contestant. He resumed his boxing career after his release, but in June 1997 he was banned from boxing and fined $3,000,000 for biting off part of the ear of Evander Holyfield during a fight. His license was restored in October 1998.