The 49ers signed Walter from their practice squad Wednesday, Keiana Martin of the team's official site reports.
Walter was elevated to the active roster ahead of last week's game against the Packers, and he appears in line for another appearance for Week 10. Both Raheem Mostert (ankle) and Tevin Coleman (knee) are not expected to play until at least Week 12, so that leaves Jerick McKinnon, JaMycal Hasty and likely Walter to man the running back corps for the next few weeks.