Anderson revived his career in 2011, recording 10 sacks. Originally drafted by the Bears in 2006, his production tailed off in recent years after his 12-sack rookie season.
Adding Anderson enhances an already formidable defensive front with Kyle Williams, Marcell Dareus and Mario Williams, who signed a six-year contract worth up to $100 million last Thursday.
Combined with a good secondary and middle linebacker Nick Barnett, defensive coordinator Dave Wannstedt's defense is shaping into one of the better ones in the NFL, at least on paper.
Other teams that expressed interest in signing the pass rusher included the Ravens, Dolphins, Titans, Jaguars and Patriots.
Buffalo also announced that they have re-signed safety Bryan Scott and receiver Derek Hagan.
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