Brunell completed 19 of 28 passes for 223 yards and did not throw an interception as Jacksonville (6-8) kept alive hopes of avoiding a third straight losing season.
"We picked ourselves up off the floor after losing three straight by a total of five points," Jaguars Coach Tom Coughlin said. "We were real excited. That game went back and forth and we were finally able to do something positive.
"I was happy we were able to put last week behind us. It's a tribute to our
players that they were able to focus on this week."
The Jaguars were helped by a key penalty.
Cincinnati owned a one-point lead when the Bengals were whistled for too many men on the field during a Jacksonville punt on fourth and six midway through the third quarter.
"Well that was a major error, no question about it. We've got coaches counting," Bengals Coach Dick LeBeau said. "We have players counting and we can't count to 11, so that kept them alive. We had a one-point lead. We were off the field and they had already punted the ball."
After the penalty, Jacksonville went for it on fourth down and Stacey Mack ran eight yards to the Cincinnati 38.
Mack then capped a nine-play, 62-yard drive with a three-yard run to give Jacksonville a 29-15 advantage.
"The offense was pretty consistent," Brunell said. "We put up 29 points. It showed a lot of character for this young offense. This win was good for this football team. I had good numbers because my teammates came to play. You get good numbers when your teammates make plays."
"It's good to be able to make a play when it's needed," Smith said. "We need to make more like it. We have the ability to do it. It's frustrating that we're out of the playoffs, but we want to finish strong. We have a chance to finish 8-8 and avoid a losing season."
The Bengals next drove to the Jacksonville 16-yard line with 5 1/2 minutes remaining. After catching a pass from Jon Kitna, T.J. Houshmandzadeh fumbled the ball into the end zone and Bengals wide receiver Danny Farmer recovered it in the end zone for an apparent touchdown.
But after a review, officials ruled Houshmandzadeh was down at the one. Cornerback Jason Craft followed with a sack for a two-yard loss and Ron Dugans was called for offensive pass interference, pushing the Bengals back to the 15. Corey Dillon had a one-yard run around a pair of incompletions, ending Cincinnati's hopes.
Dillon was limited to 59 yards on 21 carries and Kitna was 22 of 42 for 258 yards, but no touchdowns as Cincinnati (1-13) suffered its sixth straight loss.
"We seem to struggle when we get to the one-yard line for some reason," Kitna said. "We can't run it in. We can't throw it in. We're having problems. We're having to call quarterback draws to get it in. We just need to be a little more creative down there. I don't know."
Smith fell just short of his third 100-yard receiving game of the season as he had seven catches for 98 yards. Jacksonville has won eight of the last nine meetings with Cincinnati.