The signing is a coup for Nike, which fended off Adidas (ADDYY) and Under Armour (UA) - Get Report to land the top prospect, who already built a strong following during his lone amateur season with the Duke Blue Devils last year.
Williamson is the most highly touted prospect since LeBron James entered the NBA in 2003.
"I feel incredibly blessed to be a part of the Jordan Brand family," said Williamson. "Since I was a kid, I dreamed of making it to the league and having the type of impact on the game Michael Jordan had and continues to have today. He was one of those special athletes I looked up to, and I really can't express how happy and excited I am for this journey."
Nike had some egg on its face during the college basketball season after Williamson injured himself on the court during a game after one of the shoes he was wearing, another Nike brand sneaker, tore apart.
Nike shares rose 1% to $86.81 on Tuesday.