The 49ers placed Tartt on injured reserve, the team announced Friday.
Tartt suffered through an injury-plagued 2018 season due to a shoulder issue that caused him to sit out six games, including the past two.
A second-round pick of San Francisco in the 2015 NFL Draft, Tartt wound up making eight starts and registering 41 tackles with an interception and a pair of passes defensed this season.
In April, the 49ers signed the 6-1, 221-pound Tartt to a two-year contract extension.
The 26-year-old Tartt started in a career-high nine games in 2017 and recorded 54 tackles, three passes defensed, one interception and a half-sack. He went on injured reserve on Nov. 7 last year, bringing a premature end to his third season.
Tartt has appeared in 47 games, making 30 starts, in his four seasons in the Bay Area. He has notched 209 tackles, three interceptions, 3.5 sacks and 14 tackles for loss.
A native of Mobile, Ala., Tartt attended Samford University, where he was a three-time All-Southern Conference selection, appearing in 44 games and registering 277 tackles, six interceptions, 20 passes defensed and 6.5 tackles for losses in his career.