Saquon Barkley dropped a short pass that stopped the clock with 1:46 left and forced the Eagles to settle for a field goal instead of a game-sealing first down. That was plenty of time for Cousins — especially against an Eagles defense playing soft coverage with a nonexistent pass rush.
The 36-year-old veteran, playing his second game since tearing his Achilles tendon last Oct. 29 while playing for Minnesota, shook off an uneven effort and hit Darnell Mooney for 21 and 26 yards on consecutive plays during the decisive drive.
Cousins found London on a short pass to his right for the tying score, and Younghoe Koo put Atlanta (1-1) on top with a 48-yard extra point after London was flagged for unsportsmanlike conduct. The go-ahead drive took just 65 seconds.
Jalen Hurts had his final pass intercepted by Jessie Bates III to seal Atlanta's win and set off a wild celebration on the sideline.
The Eagles (1-1) went ahead on Hurts' 1-yard tush push score with 6:47 left. Barkley finished with 95 yards on 22 carries in his home debut for Philadelphia, but his drop provided the Falcons with some hope.
And then Cousins started playing like the QB Atlanta thought it was getting when it signed him to a four-year, $180 million contract.
Cousins finished 20 of 29 for 241 yards and two touchdowns. Atlanta's first TD was a 41-yarder from Cousins to Mooney, who finished with three catches for 88 yards.
Hurts was 23 of 30 for 183 yards, including a touchdown pass to DeVonta Smith. With No. 1 receiver A.J. Brown out with a hamstring injury, Smith led the Eagles with seven catches for 76 yards and a score.
Jake Elliott kicked two field goals for the Eagles. His 28-yarder with 1:39 left made it 21-15.
Atlanta kept stalling in the red zone, getting three field goals from Koo, before Cousins fired over the middle to Mooney, who shook loose from C.J. Gardner-Johnson and left him on the turf before he somersaulted into the end zone with 1:21 left in the third quarter for a 15-10 lead. Cousins failed on the 2-point conversion pass.
Hurts had some juice in his step during a second-quarter TD drive, running with abandon for big plays much like he did in the 2022 season. He spiked the ball in a rare, raw show of emotion on a 23-yard run, earning a delay-of-game penalty. He shrugged off the 5-yard setback and scrambled for 9 yards and 15 yards to move the Eagles to Atlanta's 19.
With comedian Shane Gillis and actor Bradley Cooper among the fans cheering on the Eagles, Hurts connected with Smith in the back of the end zone for a 7-yard TD that made it 7-3.
Under new defensive coordinator Vince Fangio, the Eagles have established an early knack for allowing long drives that end with three points instead of seven. Koo kicked field goals of 39, 22 and 34 yards, the last one enough for a 9-7 lead in the third quarter. In their opener, the Eagles held the Packers to just three field goals when they drove inside the 20.
Rather than take a chip-shot field goal from Elliott, the Eagles' fourth-and-4 gamble at Atlanta's 9-yard line in the first quarter failed when Hurts threw an incomplete pass.
Elliott kicked a 29-yarder with 4:31 left in the third quarter for a 10-9 lead.
Bijan Robinson ran for 97 yards for the Falcons. The Eagles stuffed him late on fourth-and-1 at the Atlanta 39.
Barkley was quiet until the go-ahead drive, a week after he rushed for 109 yards and scored three touchdowns against Green Bay. Eagles fans booed when the opening drive of the game ended without Barkley touching the ball. They went wild when he had consecutive 9-yard runs to open the second drive. Barkley had 40 yards rushing in the first half.
Former Eagles QB Nick Foles, who led the franchise to its only Super Bowl title, served as an honorary captain and led the crowd in a rendition of "Fly, Eagles, Fly."