Johnson has signed a one-year contract with the Bills, Jeremy Fowler of ESPN.com reports.
As he enters his seventh season, Buffalo will be Johnson's fourth team. He recorded 46 tackles (24 solo), two passes defensed, one forced fumble and one fumble recovery across 17 games for the Chargers last year. The journeyman will now compete for depth reps on the interior defensive line behind DaQuan Jones and Ed Oliver in the upcoming season.