Jennings was deemed expendable in Seattle with the development of Walter Thurmond and the offseason acquisition of Brandon Browner.
The Bengals have been trying to upgrade their secondary since the NFL lockout ended. Starting cornerback Johnathan Joseph left for the Houston Texans as a free agent, deciding he had a better chance to win with them. No. 3 cornerback Adam Jones is recovering from neck surgery and isn't allowed to participate in contact drills.
"It seemed like a move that was good for both clubs," Lewis said. "It's sad we had to watch Clinton walk out the door in order for it to happen, but if he (Jennings) comes in like we expect, he can play 500-600 snaps this season, even more. He gives us some more depth."
McDonald was a seventh-round choice of the Bengals in 2009. He played in eight games last season after being signed from the practice squad.
Copyright 2011 by The Associated Press