Chicago benched Cutler days earlier, having seen enough after he led the NFL with 18 interceptions and 24 turnovers in the first year of a seven-year contract he signed in the offseason. They turned to the cast-off Clausen, who hadn't started a game since 2010.
Matthew Stafford outplayed Clausen, but just barely. He completed 22 of 39 passes for 243 yards and hit the 4,000-yard mark for the fourth straight year, but it was hardly an easy afternoon for him.
Ndamukong Suh had two sacks, Calvin Johnson added six catches for 103 yards and now the playoff-bound Lions (11-4) can wrap up the NFC North title with a win next week against Green Bay. Regardless, the Lions will make their second trip to the postseason in four years and third in 16 years after Philadelphia's loss to Washington on Saturday.
They were hoping to lock up their first division championship since 1993. But with the Packers beating Tampa Bay, the division will be decided in next week's game at Green Bay.
Stafford threw interceptions in the end zone and near the goal line on back-to-back possessions in the second quarter with the Lions leading 7-0.
Reggie Bush ran for a touchdown and finished with 54 yards rushing and 44 receiving for Detroit. The Lions came away with their highest win total since they went 12-4 in 1991 and handed Chicago (5-10) its fourth straight loss.
Clausen completed 23 of 39 passes for 181 yards in his first start since his 2010 rookie season with Carolina. He threw touchdowns to Matt Forte and Alshon Jeffery and played turnover-free ball until a late interception by Glover Quin.
On the next play Bell dodged two defenders and broke a tackle by Brock Vereen for a 17-yard TD that put Detroit up 17-14. Prater added a 30-yard field goal to make it a six-point game with 2:35 remaining.
Prater gave Detroit a 10-7 lead with a 39-yard field goal on the opening drive of the second half. But the Bears answered with an 80-yard touchdown drive. Clausen capped it by lofting a 20-yard pass over Darius Slay to Jeffery in the end zone, giving Chicago its first lead at 14-10 with 2:45 left in the third.
The Bears' Jeremiah Ratliff blocked a 37-yard field goal by Prater early in the fourth, keeping it a four-point game.
The Lions might have run away with this one if not for Stafford's interceptions in the second quarter and a muffed punt by Jeremy Ross that led to a touchdown for Chicago near the end of the first half.