Johnson is averaging 20.6 points, 5.8 rebounds and 2.3 assists for the Rio Grande Valley Vipers this season. He has also had stints with the Philadelphia 76ers and Utah Jazz this season.
Johnson, 24, went undrafted in 2012 after playing four seasons at Dayton.
The Bucks (32-29) currently sit in sixth place in the Eastern Conference. Milwaukee hosts the Washington Wizards on Saturday.
- Jack Jorgensen