Chicago assigned Reed to Triple-A Charlotte and transferred right-hander Ryan Burr to the 60-day injury list in a corresponding move.
Reed, 26, was designated for assignment by Houston last week. He had been with the Astros organization since they selected him in the second round of the 2014 amateur draft.
The 6-foot-4, 270-pound Reed was hitting .224 with 12 homers, 35 RBIs and 33 runs in 56 games at Triple-A Round Rock this season. Reed had a solid 2018, when he was named a Pacific Coast League All-Star and hit .255 with 28 homers and 108 RBIs in 123 games at Triple-A. He also had a .374 on-base percentage and a .540 slugging percentage.
Reed has struggled in his brief stints in the big leagues with the Astros, hitting .153 with three homers and eight RBIs in 48 games across 2016 to 2018.
Reed is a career .282 hitter with 135 homers and 478 RBIs in six minor league seasons.