The Chargers took advantage of a missed field goal from Robbie Gould to take the lead in the first quarter when quarterback Philip Rivers lofted the ball to Danny Woodhead at the back of the endzone for a 14-yard score.
San Diego extended their lead when Bears quarterback Jay Cutler was intercepted by Jason Verrett when attempting to find Alshon Jeffery down the sideline and the cornerback returned the ball 68 yards for a touchdown.
Cutler got the Bears on the scoreboard after firing deep to Jeffery to get his side to the goal line before he faked a running play to fire to Martellus Bennett.
However, the Chargers went nine points ahead just before the break when Josh Lambo kicked a field goal between the posts from 39 yards.
The visitors drove down the field in the early stages of the second half, but were held out of the endzone. Matters were made worse for John Fox's men when Gould missed his second kick of the match from 34 yards.
At the start of the fourth quarter, the Bears got back into the match when Jeremy Langford finished a solid drive from Cutler as he plowed in on the goalline for a one-yard score.
San Diego came close to putting the game beyond the reach of the visitors on their next drive, but penalties from Stevie Johnson and DJ Fluker cancelled out a touchdown, limiting the home side to a field goal from Lambo.
The Bears capitalised on their missed chance to take the lead for the first time in the game when Cutler threw over the middle for Zach Miller, who made an impressive one-handed catch to complete a 25-yard touchdown. Langford made it a three-point game as he charged through the line for the two-point conversion.
Rivers had time to lead a comeback, but his attempt was ended when he was sacked on back-to-back plays by Lamarr Houston, which secured the win for the visitors.
The Bears moved to 3-5 as a result of their win, while the Chargers drop to 2-7 in their season.