The Diamondbacks released Karcher on Sunday.
Karcher signed a minor-league contract with the Diamondbacks on Nov. 17.
Karcher elected free agency Tuesday, Charlie Goldsmith of The Cincinnati Enquirer reports.
Karchar cleared waivers and was outrighted to Triple-A Louisville on Monday.
Karcher was designated for assignment by the Reds on Thursday, Charlie Goldsmith of The Cincinnati Enquirer reports.
Karcher was optioned to Triple-A Louisville on Tuesday.
Karcher picked up the save in Monday's 5-4 victory over Kansas City, tossing a scoreless inning in which he allowed zero hits and one walk. He didn't record a strikeout.
Karcher was recalled from Triple-A Louisville on Friday.
Karcher was optioned Tuesday to Triple-A Louisville by the Reds, C. Trent Rosecrans of The Athletic reports.