Bowman spent six-plus seasons with the Niners, who selected him in the third round of the 2010 draft, before getting traded to the Oakland Raiders in October 2017. He sat out the entire 2018 season as a free agent.
The 31-year-old Penn State product racked up 140 combined tackles in four consecutive active seasons for San Francisco starting in 2011. He missed the entire 2014 campaign because of injury. He earned four first-team All-Pro selections and three Pro Bowl nods during that span.
Bowman enjoyed a resurgence after joining the Raiders in 2017 and finished the year ranked 11th among linebackers in Pro Football Focus' grades.
In December 2017, the Maryland native expressed interest in continuing his career, either with the Raiders or another team and felt he could still make a serious impact.
"I still study the same way," Bowman told reporters. "I still feel like I can play this game at a high level. I feel like I can average 10 tackles a game. I don't see why they wouldn't sign me back. I'd love to stay. I like the area. I like the team and the organization. Hopefully we can make it happen."
Bowman finishes his career with 798 total tackles, 29 passes defended, 14 sacks, seven forced fumbles and five interceptions in 99 games.