After a slow start, the Patriots threatened multiple times but the Bears came away with three crucial interceptions to seal their third win of the year.
Chicago quarterback Justin Fields got the visitors off to a strong start, putting together drives that ended in a field goal and a rushing touchdown to open up a 10-point deficit after the first quarter.
Meanwhile, New England's starting quarterback Mac Jones was unable to penetrate a relentless Chicago defence.
It was not until the 2021 Pro Bowler was benched and replaced with rookie Bailey Zappe that the Patriots finally broke through.
Zappe immediately connected with wide receiver Jakobi Meyers on a 30-yard touchdown pass, then set up Rhamondre Stevenson for a rushing score to put the hosts up 14-10.
Chicago's defence would ensure that was where New England's scoring stopped, while the Bears ran in 23 unanswered points en route to arguably their best win of the season.