Williamson posted on his Instagram that he would take his skills to the next level.
Williamson was the AP Player of the Year, Naismith Award winner and Wooden Award winner among his many accolades this season.
He is widely projected as the top overall pick in the June draft.
The 6-foot-7, 285-pound Williamson captivated all of college basketball with his freakish, once-in-a-generation athleticism, his energy at both ends of the floor and his omnipresent charisma.
The Atlantic Coast Conference player and rookie of the year averaged 22.6 points - tied for the league lead with fellow Duke freshman RJ Barrett - and 8.9 rebounds. Along the way, he became the face of college basketball this season, routinely coming up with at least one highlight-reel play or show-stopping dunk per game.
His decision to turn pro came as no surprise. In fact, he spent the season greeting NBA chatter with a playful wink and a knowing nod.
He said it would be "dope" to play on a hypothetical New York Knicks team with Kyrie Irving and Kevin Durant. Upon learning that LeBron James and Stephen Curry were talking about him during All-Star weekend, he responded that he's "hoping to be there competing against them next year."
During his lone college season, he helped the Blue Devils earn the No. 1 ranking in the final AP Top 25 and the top overall seed in the NCAA tournament. Duke was knocked out by Michigan State in the East Regional final.
Now that he's headed to the NBA, one key subplot to follow is which sneaker company will land his endorsement.
In one of the signature moments of the season, Williamson blew out his left Nike shoe - the PG 2.5, the signature shoe of Oklahoma City star Paul George - and sprained his right knee in the opening minute of what became a lopsided home loss to rival North Carolina.
The impact was immediate - Nike's stock price took a hit the next day, and the shoe company sent a team of representatives to campus to investigate. When Williamson returned roughly three weeks later for the ACC Tournament, he wore a pair of modified size-15 Nikes from the signature line of Irving, a Boston Celtics All-Star and former one-and-done player at Duke.
Williamson joins Blue Devil teammates Cam Reddish and Barrett as classmates headed to the pros after one season. Point guard Tre Jones said he will return to school for his sophomore year.