Early in his boxing career, Tim Witherspoon briefly worked as a sparring partner for Gerry Cooney. "I lasted three days," Witherspoon said. "When I bloodied his nose, they told me to take a walk. In 1983, Witherspoon fought Larry Holmes for the World Heavyweight Championship and lost by a twelve-round split decision. In 1984, he defeated Greg Page by a twelve-round majority decision to win the vacant WBC Heavyweight Title. He lost it in his first defense, dropping a twelve-round majority decision to Pinklon Thomas. In 1986, Witherspoon overpowered Tony Tubbs by a fifteen-round majority decision to win the WBA Heavyweight Title. He successfully defended it with an eleventh-round TKO of Frank Bruno, but lost it in his second defense when he was stopped in the first round by James (Bonecrusher) Smith.