Shams Charania of Stadium and The Athletic reported the deal, which was completed via waiver claim.
Ball joined the Blue in late December as a practice player.
The 21-year-old shooting guard is the younger brother of New Orleans Pelicans point guard Lonzo Ball and the older brother of prized prospect LaMelo Ball, a projected top-five pick in the 2020 NBA draft.
Ball joined UCLA in 2017 but never made an appearance for the Bruins after receiving an indefinite suspension for a shoplifting arrest while the team was in China for an international game. He left the program and entered the 2018 draft but didn't get selected.
He spent time in 2018 with BC Prienai in Lithuania and Los Angeles Ballers of the Junior Basketball Association, a league founded by his father, LaVar Ball. He went unsigned for most of 2019 before joining OKC's G League club.
Ball gained 14 games of professional experience with Prienai. He averaged 12.6 points, 2.9 rebounds and 2.4 threes while shooting 42.5 percent from the field but a more promising 41.5 percent on threes.
The guard's outspoken father, LaVar Ball, predicted during an appearance on Fox Sports 1's Undisputed his son is a future NBA scoring champion:
Ball is a long way from fulfilling that prophecy, but landing a G League contract is a major step in the right direction for his pro career.
He'll spend the rest of the campaign trying to prove that, at minimum, he can be a valuable offensive role player off the bench thanks to his outside shooting prowess.