"A.J. hasn't had the opportunity to play football for the last three years while resolving a serious legal matter," Broncos general manager John Elway said in a statement. "We've had several conversations with him since he's been cleared and have become very familiar with his background and character. Our organization is confident A.J. is ready to move forward and resume his playing career."
Johnson and former Tennessee teammate Michael Williams were indicted in February 2015 after a woman accused both men of raping her during a party at Johnson's apartment in November 2014. Tennessee suspended Johnson and Williams two days after the party and neither played for the Volunteers again.
Attorneys for Johnson and Williams argued during the trial that the woman had consensual sex with both men before lying about the incident.
Johnson was a three-time All-Southeastern Conference selection from 2011-14 and ranks second all-time in tackles at Tennessee (425). To make room on the roster, the Broncos released linebacker Stansly Maponga.
In addition, the Broncos signed safety Shamarko Thomas and placed safety Jamal Carter on injured reserve. Thomas was cut by the Indianapolis Colts two days after he became the first player ejected for violating the NFL's expanded helmet rules during a game against the Seattle Seahawks on Thursday night.