The Cardinals placed Johnson (neck) on injured reserve Wednesday, Darren Urban of the team's official site reports.
Johnson suffered a neck injury in the 31-7 loss to the Seahawks in Week 2. He was placed on injured reserve, so he is guaranteed to miss at least four games. However, the 23-year-old isn't expected to play again this season. If that's the case, he will finish the year with eight total tackles (three solo), one fumble recovery and one pass defended. Without Johnson, Garrett Williams (Achilles), who has yet to play this season, could take on a larger role upon his return. Max Melton (toe), Kei'Trel Clark and Starling Thomas, the latter who was promoted from the practice squad, may also be more involved.