Johnson secured a spot on Buffalo's 53-man roster Tuesday, Joe Buscaglia of The Athletic reports.
Johnson was one of three running backs to make the team, joining starter James Cook and rookie fourth-round draft pick Ray Davis. Johnson and Davis are expected to split backup duties. Cook and Davis are listed at 210 and 220 pounds, respectively, so both backups are better suited for short-yardage work than the 190-pound Cook, though 237-pound quarterback Josh Allen often calls his own number in such situations.