Mancini signed a minor-league contract with the Reds on Wednesday, Mark Sheldon of MLB.com reports.
Mancini was dropped by the Cubs at the start of August after putting up a .234/.299/.336 slash line through 261 plate appearances. The 31-year-old will now serve as organizational depth for the Reds and could work his way back into a major-league bench role if his bat heats up in Triple-A.