The 49ers activated Mitchell (knee) from injured reserve Saturday, Field Yates of ESPN reports.
Head coach Kyle Shanahan indicated earlier in the week that Mitchell was on track to rejoin the 53-man roster, locking in the talented second-year back as the backup to Christian McCaffrey. It'll be interesting to see how the 49ers use Mitchell alongside the new Panthers import, as it's possible the duo could both see a plethora of carries with McCaffrey taking every opportunity on passing downs.