Maualuga, 28, was drafted by the Bengals in the second round in 2009.
"Rey is a physical force on the field and a great teammate in our locker room," Bengals head coach Marvin Lewis said in a team release. "He's a hard-working, dedicated player who continues to get better. As we have put together playoff teams the last four years, we've said more than once that a huge key is keeping productive players who know our system, and this is another big step in that plan."
One of the few linebackers the Bengals have actually drafted in recent seasons -- others such as Vincent Rey, Emmanuel Lamur, Jayson DiManche and Vontaze Burfict were all undrafted free-agent signings -- Maualuga has been viewed as a cornerstone of the defense. The Bengals hoped to use the middle linebacker as one of the focal points of their defense when he was first selected. They maintained that view of him in 2013 when he was re-signed to a two-year contract extension.
Injuries have been a problem for Maualuga throughout his career, particularly in the past two seasons. He had a knee injury in 2013 that forced him to miss three games. This past season, a hamstring injury kept him out of four.
When he was on the field last season, Maualuga recorded 59 tackles and an interception.
He had a clear impact on the Bengals' run defense. When Maualuga was on the field, opposing running backs averaged just 3.6 yards per carry. When he wasn't, they averaged 4.9 yards.
Back in January, Bengals defense coordinator Paul Guenther said he hoped that Maualuga would stay in Cincinnati.
"I like Rey as a player. I always have," the former Bengals linebackers coach said. "I know he gets a bad rap around here and has in the past some, but he played damn good when he was in there, so I hope to have him back."