Tartt agreed to terms on a one-year deal that will keep him in San Francisco for a seventh season, the team announced.
“We are very excited to have Jaquiski back with our team,” general manager John Lynch said in a statement. “Jaquiski is an extremely skilled and versatile player who provides excellent communication skills for our defense. Welcome back Quiski!”
The Niners also agreed to terms on a one-year deal with safety Tavon Wilson earlier Monday. Wilson is expected to compete for a roster spot.
Along with Tartt, the Niners have spent most of their free-agent resources in retaining left tackle Trent Williams, fullback Kyle Juszczyk, cornerbacks Jason Verrett and Dontae Johnson, and defensive tackle D.J. Jones.
The 49ers originally selected Tartt in the second round of the 2015 NFL draft.
Tartt’s time with the Niners has been interrupted by injury, including shoulder, forearm and toe issues. He ended three seasons on injured reserve and appeared in just 36 of a possible 64 games over his past four seasons with the team.
In 2020, Tartt landed on injured reserve in November because of turf toe that limited him to 30 tackles and an interception in seven games.
Tartt, 29, has 301 tackles, four interceptions and four sacks in 66 games.