Per C. Trent Rosencrans of The Athletic, Hamilton won't be tendered a contract for 2019 by Friday's 8 p.m. ET deadline.
Hamilton was entering his final year of arbitration with the Reds. The 28-year-old was projected to earn $5.9 million next season, per Tim Dierkes of MLB Trade Rumors.
Known for his lightning speed, Hamilton has struggled with the bat since being called up from the minors in September 2013. He owns a .245/.298/.333 slash line with 277 stolen bases in 690 games.
Despite Hamilton's offensive shortcomings, he still has value on defense because of his speed. The Mississippi native ranks fourth among all MLB outfielders in Ultimate Zone Rating (45.1) and eighth in defensive runs saved (50) since 2014, per FanGraphs.
Teams in need of a fourth outfielder will likely be intrigued by Hamilton's ability to handle center field and his speed off the bench now that he is a free agent.