Cutler completed 22-of-32 passes with an interception for the Bears (1-0), who are looking to build off an 11-5 campaign which included an NFC North crown and appearance in the conference title game.
Forte racked up 68 yards rushing on 16 carries and five receptions for 90 yards and a score, while Robbie Gould kicked three first-half field goals and Brian Urlacher returned a fumble for a touchdown in Chicago's second straight home-opening victory.
"The offense just took care of business and put points on the board. Defensively, we just had to follow our franchise player," said Bears head coach Lovie Smith on his club's successful opening contest.
Matt Ryan went 31-of-47 for 319 yards and was picked off once for the Falcons (0-1), who finished 13-3 a season ago and won the NFC South.
Michael Turner gained 100 yards on 10 carries, also contributing 40 yards on three receptions. Kroy Biermann returned an interception 50 yards for Atlanta's lone score on Sunday. The Falcons lost in Chicago for the first time since 2005.
Early in the second quarter, the Falcons started in the shadow of their own goal line, and Ryan was sacked at the one on third down. Devin Hester returned the punt to the visitors' 30, but a seven-play drive only netted a 23-yarder from Gould for a 13-3 game.
Later in the period, a 14-play, 72-yard drive ended as Gould converted his third field goal of the half, a 26-yarder with under a minute left, and Chicago led 16-3 at the break.
On the Falcons' first series of the second half, Turner exploded for a 53-yard dash to the Chicago 32, but the drive stalled and Matt Bryant hit from 25 yards out.
Hester's 53-yard catch-and-run to the one on the Bears next series preceded a TD strike to Matt Spaeth for a 23-6 Chicago edge with 6:55 left in the quarter. Three plays later, Ryan was sacked by Julius Peppers and lost control, with Urlacher picking up the ball and going 12 yards for a touchdown.
The Falcons only answer came when Biermann picked off Cutler and raced 50 yards for a touchdown, but the conversion failed and Atlanta was behind 30-12 with 10:23 remaining.
Atlanta's final drive stalled with 2:42 to play as Ryan's pass on 4th-and-10 from the Chicago 15-yard line fell incomplete.
"I'm disappointed, but not discouraged," offered Falcons head coach Mike Smith. "It's gonna be a long season, this was just Week 1. We will work to get this fixed and we will get on the right track."
Gould capped Chicago's opening drive with a 41-yard field goal, and Bryant countered for Atlanta on the ensuing possession on a 48-yard make.
Ryan was picked off by Urlacher on the Falcons' ensuing series, and the Bears took over on their own 28. Cutler then found Forte in the flat on a 1st-and-10 from the Bears' 44, and he rumbled down the right sideline for a 56-yard score and a 10-3 lead.
Chicago took a 13-12 lead in the all-time series...The Bears, who were held to 22 yards rushing in the first half, finished with 88 yards on the ground and were outgained in victory by a 386-377 margin...Atlanta has scored just 21 points in losing its last two season-openers on the road (15-9 loss in overtime at Pittsburgh in 2010)...The Bears travel to New Orleans and the Falcons welcome the Eagles in Week 2.