The Marlins designated Mitchell for assignment Wednesday, Christina De Nicola of MLB.com reports.
Mitchell's contract was selected by the Marlins on Thursday, Jordan McPherson of the Miami Herald reports.
Mitchell signed a minor-league contract with the Marlins on Thursday.
Mitchell was released by the Phillies on Thursday, Andersen Pickard of MLBDailyDish.com reports.
The Phillies reassigned Mitchell to their minor-league camp Monday, Todd Zolecki of MLB.com reports.
Mitchell agreed Tuesday with the Phillies on a minor-league contract, Jayson Stark of The Athletic reports.
Mitchell was released by the White Sox on Monday, James Fegan of The Athletic reports.
Mitchell was added to the White Sox's 60-man roster Tuesday, James Fegan of The Athletic reports.
Mitchell signed a minor-league contract with the White Sox on Thursday, Ken Rosenthal of The Athletic reports.
Mitchell was outrighted to Triple-A El Paso on Monday.