The NFL Network reported that Barkley suffered a grade 3 strain of the medial collateral ligament. The injury to Barkley solidified Jeff Driskel's chances to open the regular season as Dalton's backup.
Cincinnati trimmed its roster down to the league-mandated 53 players on Saturday. Along with placing Barkley on IR, the most notable move was the release of veteran defensive end Michael Johnson.
A member of the Bengals since he was selected in the third round of the 2009 NFL Draft, Johnson started at least 15 games in six of the past seven seasons.
The 6-foot-7, 280-pound Johnson had 49 tackles and 5.0 sacks in 2017, boosting his career total to 44.0 sacks in 140 games. However, the Bengals offered a hint of his future with the team by signing fellow defensive linemen Geno Atkins and Carlos Dunlap to contract extensions earlier this week.
Cincinnati also cut loose a pair of cornerbacks, releasing C.J. Goodwin and waiving Josh Shaw with an injury designation.
Barkley misfired on all three pass attempts before he was injured in Thursday's 27-26 loss to the Colts. He was signed to a two-year deal by the Bengals in March.
A fourth-round draft pick of the Philadelphia Eagles in 2013, Barkley started the final six games for the Bears in 2016, finishing with a 1-5 record and throwing for 1,611 yards with eight touchdowns versus 14 interceptions.
Driskel replaced Barkley in Thursday's game and completed 14 of 20 passes for 116 yards and a 20-yard touchdown pass to Josh Malone.
Selected by the 49ers in the sixth round of the 2016 NFL Draft, Driskel suffered a broken thumb in Cincinnati's final preseason game a year ago and spent the season on injured reserve. He has never appeared in an NFL game.
Driskel spent parts of four seasons at Florida before winding up his college career at Louisiana Tech, throwing for 4,026 yards and 27 touchdowns in 2015.