Kelly spent his first 10 seasons with the Buccaneers, netting 23 career interceptions and earning a Super Bowl ring in 2002.
Kelly paid $450,000 to void the final season of his contract so he could test free agency.
By signing with Detroit, Kelly reunites with head coach Rod Marinelli and defensive coordinator Joe Barry, both of which are former Bucs assistants.
Kelly will also play with three former teammates — safety Kalvin Pearson, defensive tackle Chuck Darby and safety Dwight Smith. Pearson, a restricted free agent, will become a Lion next week if the Bucs choose not to match the Lions' contract offer.
It's always been assumed that Cato June would take Derrick Brooks' place at weak side linebacker once the future Hall of Famer retired. But is that really the case? Or is there another play afoot at One Buc Place? Bucsblitz.com examines that, with the help of insider information from Scout.com's Senior NFL reporter Adam Caplan. Click here for this expert analysis.
Bucsblitz.com's Editor, Matthew Postins, has published his first Buccaneers Mock Draft. See who Postins selected for every Buccaneers pick, get expert analysis and possible alternatives at each selection. Just click here and take a look.
Want to sound off about this mock draft? Have an opinion? Express it at the Bucsblitz.com message board. Just click here and look for the "Bucs Mock Draft 1.0 unveiled" post.
Matthew Postins covers the Buccaneers for BucsBlitz.com and the Charlotte Sun-Herald in Port Charlotte, Fla. An award-winning member of the Pro Football Writers Association, he appears frequently on Scot Brantley Show from 3-6 p.m. weekdays on WHBO 1470-AM in Tampa-Clearwater.