To make room for Bowman, the team placed tight end Vance McDonald on season-ending injured reserve.
Bowman, whose 21-day evaluation period window closed Tuesday, has yet to practice, so it is doubtful he plays this weekend at Seattle. But being on the active roster allows him to practice and brings sorely needed leadership to the Niners' defense.
"I'm going to get out there when I feel 100 percent, let's be clear on that,'' Bowman said Tuesday. "Throughout this rehab process, I've been doing everything to get me this far. Now it's time for some football activity, some quick-reaction, things like that. Of course I want to be there, if I'm ready to go. It just comes to if I'm ready. I'm listening to the doctors. They're being great, cautious about what I do. As far as me, once I'm out there, I don't know how to go slow. I just know one speed.''
Bowman still is recuperating from torn ACL and MCLs in his left knee suffered in last January's NFC Championship Game loss to the Seahawks.
The Associated Press contributed to this report.