Shams Charania of The Athletic and Stadium reported the news Wednesday.
Financial details of the agreement are unknown. In December, NBL analyst Corey Williams reported Ball received an offer of $100 million.
The contract will make him the first Ball brother to sign a deal with a company outside of the family's Big Baller Brand, per Charania.
Ball has taken an unorthodox path to the cusp of the NBA. He left high school in 2018 to play for Vytautas Prienu in Lithuania and most recently played for the Illawarra Hawks in Australia.
The 19-year-old California native told ESPN's Tim Keown that he's ready to find a permanent home.
"It's not like you get to the league and then, 'Oh, I made it,'" he said. "No—now life's finally started."
Ball is a unique prospect. He combines a 6'7" frame with a guard skill set that could make him a matchup nightmare should his jump shot develop after he struggled with his three-point shooting in Australia. His upside was still on display as he won NBL Rookie of the Year honors.
He'll likely be a top-five selection when the draft takes place Oct. 16, and there's a chance he will be picked first by the Minnesota Timberwolves. Anthony Edwards, James Wiseman and Deni Avdija are the other candidates for the No. 1 slot.
The reported Puma contract means he's already secured a significant payday before even entering the NBA.