Indiana State coach Mike Sanford announced the transfer Wednesday, although the university's release did not mention the reason for the redshirt season. Players dropping from the FBS to the FCS level in the offseason are usually eligible the next season.
As a sophomore last year, Allen was Indiana's leading tackler with 74 stops and was an honorable mention All-Big Ten selection. He had one sack, 3 1/2 tackles for loss, two interceptions and one pass breakup.
In June, Allen was arrested in Bloomington and charged with selling cocaine and heroin with a firearm - Level 2 felonies - as well as dealing methamphetamine, a lesser charge. Indiana subsequently kicked him off the team.
The former four-star recruit from Indianapolis began his Hoosiers career in 2013 and was selected to the Big Ten All-Freshman team.