The rookie star received daily tests for COVID-19 while away from the team and produced negative results for each one, according to the Pelicans.
Williamson left the Walt Disney World Resort on July 16 for what the team referred to as an "emergency family medical matter."
While the NBA didn't announce how long Williamson's quarantine period will last, he could be required to isolate for four days after having been away from the NBA bubble for eight days, according to ESPN's Tim Bontemps.
Because of that, Williamson may not be allowed to play in the Pelicans' July 30 restart opener against the Utah Jazz for cautionary reasons, a source told ESPN's Andrew Lopez.
The 20-year-old didn't make his NBA debut until Jan. 22. He's averaging 23.6 points and 6.8 rebounds on 59% shooting in 19 games.