The Braves' outfield has been hit hard by injuries, with Ender Inciarte (hamstring), Nick Markakis (wrist) and Austin Riley (knee) all on the injured list. Inciarte and Markakis are not expected back anytime soon.
Hamilton, 28, hit .211 with 12 doubles and 12 RBIs for the Royals this season, and his stolen base total dropped to 18. He swiped 56 bases in 2014 and increased his total by one in each of the next three seasons.
The switch-hitter signed with the Royals in December after spending the first six seasons of his major league career with Cincinnati, where he was a five-time Gold Glove finalist in center field. Hamilton has 295 career stolen bases, fifth-most of any active player.
To make room for Hamilton, the Braves optioned right-hander Bryse Wilson to Triple-A Gwinnett and recalled RHP Jacob Webb from the Stripers and placed him on the 60-day injured list with a right elbow impingement.
Hamilton had a $4.6 million salary on the last-place Reds. Because this was a waiver claim, the Braves must pick up the remainder of Hamilton's salary.
The Associated Press contributed to this report.