The 33-year-old Augustin spent the past four seasons with the Orlando Magic after previous stints as a member of the Charlotte Bobcats, Indiana Pacers, Toronto Raptors, Chicago Bulls, Detroit Pistons, Oklahoma City Thunder and Denver Nuggets.
After playing an integral role in Orlando's run to the playoffs in 2018-19, Augustin's spot in head coach Steve Clifford's rotation changed last season.
Markelle Fultz was given the keys to the starting point guard job, which resulted in Augustin going from starting 81 games in 2018-19 to 13 games last season.
Even so, Augustin was a productive player off the bench last season, averaging 10.5 points, 4.6 assists and 2.1 rebounds in 57 appearances.
Augustin is primarily accustomed to coming off the bench as an NBA player with 320 starts in 864 regular-season games.
Over the course of his career, the journeyman guard has averaged 9.9 points, 4.0 assists and 1.9 rebounds per contest.
He has averaged double figures in scoring in each of the past three seasons, marking the first time in his 12-year NBA career that he has accomplished that feat.
The Bucks' success in 2020-21 will largely depend on how Giannis Antetokounmpo and Khris Middleton mesh with Holiday, but Augustin will play a significant role in his own right, especially if injuries force him into a starting role at any point.