"We got better today. Our football team got better. I am very happy," general manager Ozzie Newsome said. "This will allow Ray to finish his career as a Raven."
"We have an agreement in principle with Ray Lewis," Ravens spokesman Kevin Byrne said. "It will allow Ray to finish his career as a Raven."
By keeping Lewis, the Ravens fill the void created at inside linebacker when Bart Scott signed with the New York Jets.
Lewis earned his 10th Pro Bowl this season after leading the NFL's second-ranked defense with 160 tackles. He also had 3½ sacks, three interceptions and two fumble recoveries.
The Ravens also reached an agreement with Minnesota Vikings' six-time Pro Bowl center Matt Birk.
"Matt Birk agreed to a three-year contract, which will be signed in the morning," Byrne said.
Birk replaces last year's starting center, Jason Brown, who signed a five-year, $37.5 million contract with the St. Louis Rams.