The Bears (10-6) still need a Minnesota loss to Green Bay to reach the postseason. The win by Chicago eliminated the defending champion New York Giants from the playoff picture.
The Lions (4-12) lost their last eight games and turned the ball over four times in the finale. Calvin Johnson fell short in his attempt to become the first player with 2,000 yards receiving in a season.
Detroit trailed 20-3 late in the first half but pulled within two and had the ball at its own 9-yard line before a three-and-out forced a punt.
The Bears ran out the last 3:40, with Cutler's 19-yard run on third down keeping the drive going.
Johnson, who broke Jerry Rice's record of 1,848 yards receiving the previous weekend, finished at 1,964 after catching five passes for 72 yards.
Detroit's Matthew Stafford went 24 of 42 for 272 with three touchdowns and an interception.
The Lions scored two straight touchdowns to make it 20-17 in the third quarter, but Chicago which came into the game with a league-high 40 takeaways forced another turnover.
Stafford's fumble gave the Bears the ball at the Detroit 13. It was the fourth time the Bears started a drive inside the Detroit 25, and they ended up kicking a field goal.
Olindo Mare added another field goal, a 20-yarder with 10:47 left in the fourth, to make it 26-17. Stafford's 9-yard touchdown pass to Brian Robiskie pulled Detroit closer, but it wasn't enough.
Cutler threw a 55-yard pass to Alshon Jeffery to the Detroit 27 on Chicago's first play from scrimmage, delighting the many Chicago fans in attendance at Ford Field. But that drive stalled, and the Bears actually had to punt after Cutler fumbled on third down and the ball was recovered back at midfield.
After the Lions kicked a field goal, Chicago struck back when Cutler swung a pass out to Earl Bennett, who made the catch behind the line of scrimmage, got a block and outran the defense for a surprisingly easy 60-yard touchdown.
Joique Bell fumbled away the ensuing kickoff, and the Bears kicked a field goal. In the second quarter, Stafford fumbled deep in his own territory. Julius Peppers recovered for Chicago, and his short return gave the Bears the ball at the 10.
After a third-down pass interference call on safety Don Carey, Matt Forte scored on a 1-yard run to make it 17-3.
The Lions weren't done giving the ball away. Tim Jennings picked off Stafford's overthrown pass, and his 31-yard return to the Detroit 23 set up another field goal.
Stafford's 25-yard scoring pass to Kris Durham with 12 seconds left in the half made it 20-10, and he threw a 10-yarder in the third to Will Heller.