Financial terms were not disclosed. Curtis made just over $530,000 last year.
Curtis, who's entering his sixth season, will start at left linebacker in place of Steve Foley, who will be sidelined for the entire campaign with a dislocated shoulder.
"Maybe not for the season opener, but as far as going in there and stepping in when somebody goes down it's the same old thing," said Curtis, who is scheduled to make $550,000 this season, according to the Cincinnati Post. "I'm excited about it."
In 16 games last season, Curtis made 26 tackles. He had seven in four preseason contests this year, and has played in 46 of the last 48 Bengals games.
He was Cincinnati's sixth-round draft pick out of West Virginia in 1997.