The 49ers placed Johnson (knee) on their practice squad injured reserve Tuesday, per the team's official site.
Johnson suffered an unfortunate ACL tear during Sunday's win over the Buccaneers, and he'll now spend the next several months rehabbing and preparing for the start of the 2023-24 campaign. The 31-year-old cornerback appeared in two games this season for San Fransisco but didn't record any stats.