The Browns waived tight end Orson Charles on Sunday in a corresponding move.
Gathers, a former Baylor basketball player, was drafted in the sixth round of the 2016 draft by the Cowboys, but his status on the roster became more tenuous when 11-time Pro Bowler Jason Witten came out of retirement after a year in broadcasting. Gathers also missed time at training camp with an ankle injury.
Gathers was suspended for one game by the NFL earlier this year for violating the NFL's substance abuse policy. He was arrested and charged with possession of marijuana by Frisco, Texas, police before the start of last season. In March, Gathers reached a deal with the district attorney, reducing the charge to a Class C misdemeanor, 90 days' deferred adjudication and a fine.
Gathers hadn't played football in a decade when he decided after four years in the Baylor basketball program that he would make himself eligible for the NFL draft. One of the best rebounders in Big 12 history was a long shot to get taken, but the Cowboys grabbed the 6-foot-6 Gathers with their final pick in the sixth round in 2016.
After a year on the practice squad and a season on injured reserve because of symptoms from a concussion, Gathers made the team last year. He played in 15 games with four starts, catching three passes for 46 yards.
ESPN's Todd Archer and The Associated Press contributed to this report.