The 49ers signed Vaughn on Wednesday, Nick Wagoner of ESPN.com reports.
The 2020 third-round pick out of Vanderbilt spent the first four seasons of his career in Tampa Bay and has now agreed to terms with San Francisco. Vaughn is expected to add depth to a 49ers running back room dealing with injuries to Christian McCaffrey (calf), Elijah Mitchell (hamstring) and Isaac Guerendo (hamstring).