Jennings has appeared in seven games this season for the Wisconsin Herd, who are the Bucks' G League affiliate.
Jennings averaged 21.4 points, 7.6 assists and 4.7 rebounds per contest in G League action.
Prior to joining the G League's Herd, Jennings spent time playing for the Shanxi Brave Dragons of the Chinese Basketball Association in 2017.
In 541 career NBA contests, the 28-year-old owns per-game averages of 14.3 points, 5.7 assists and 3.0 rebounds.
His best campaign came in 2011-12 when he put up 19.1 points, 5.5 assists and 3.4 rebounds per game for the Bucks. Last season, Jennings posted 7.1 points, 4.9 assists and 2.4 boards per contest in time split between the Knicks and Wizards.
With Matthew Dellavedova (ankle) and Malcolm Brogdon (torn quad tendon) still out due to injury, Jennings will provide the Bucks with depth at point guard behind starter Eric Bledsoe.