Lawson spent his first five NFL seasons with the San Francisco 49ers after they picked him 22nd overall in the 2006 draft. His best season was in 2009, when he posted 51 tackles and 6.5 sacks, but the 49ers refused to give him a contract extension last season, signaling that his time in San Francisco likely was up.
Lawson is the second defensive starter to go from the 49ers to the Bengals in the past few days. Cornerback Nate Clements, an 11-year veteran, agreed to terms with the Bengals on a two-year deal Saturday. Clements is an Ohio native who played at Ohio State.
In Cincinnati, Lawson is expected to solidify defensive coordinator Mike Zimmer's linebacking corps, which had been looking thin. Rey Maualuga will have to adjust to middle linebacker this year, Keith Rivers is out indefinitely after offseason wrist surgery, and backup Roddrick Muckelroy ruptured his Achilles on Saturday, which will sideline him for the year.