Flowers, 24, was the ninth overall pick in 2015 by the New York Giants but never played at the high level expected of a top-10 pick.
He started 49 of the 52 games in which he played for the Giants from 2015-18 at left tackle but lost his starting job last season in Week 3 to Chad Wheeler, who signed with the Giants as an undrafted free agent in 2017.
The Giants cut him on Oct. 10 and the Jaguars signed him two days later to a one-year contract worth $705,000. A rash of injuries along the offensive line forced him into the starting lineup and he ended up starting the final seven games of the season.
ESPN's Michael DiRocco contributed to this report.