Mitchell was placed on waivers by the Bruins on Friday, Elliotte Friedman of Sportsnet reports.
Mitchell was placed on the injured non-roster list for an undisclosed reason Monday, Mark Divver of the New England Hockey Journal reports.
Mitchell signed a one-year, two-way contract with Boston on Sunday, per Conor Ryan of The Boston Globe.
Mitchell was recalled from AHL Providence on Thursday.
Mitchell was placed on waivers by the Bruins on Friday, Elliotte Friedman of Sportsnet reports.
Mitchell was recalled from AHL Providence on Saturday, Mark Divver of the New England Hockey Journal reports.
Mitchell was loaned to AHL Providence on Sunday.
Mitchell was summoned from AHL Providence on Tuesday.
Mitchell was demoted to AHL Providence on Monday, per CapFriendly.
Mitchell was brought up from AHL Providence on Sunday.