Listed at 6-foot-2 and 280 pounds, Fluellen has seven years of NFL experience spent mostly with the Detroit Lions.
He's a career backup, who had two sacks in eight games with the Lions last season. Overall, the 2008 third-round draft pick has 4-1/2 sacks, 12 quarterback hits and 10 tackles for a loss in 77 career games, including six starts.
The signing was announced Tuesday, when Buffalo opened a three-day mandatory minicamp.
Safety Deon Broomfield was designated waived/injured to make room for Fluellen's addition.
AP NFL website: www.pro32.ap.org and www.twitter.com/AP-NFL