The two-time champion ran among the top five for most of the 400 miles after recovering from a poor qualifying that left him only 26th on the grid. By halfway through Stewart was already running behind the leaders but only when the caution waved for the sixth time, due to debris on the track, did he emerge as a serious contender for victory.
With 52 laps still remaining when the leaders pitted for the final time under the caution, it looked uncertain whether anyone would be able to drive to the chequered flag without stopping for a splash of fuel. Michael Waltrip Racing's Martin Truex gambled on staying out and took the lead, hoping for a further caution that was never waved in the end.
As the lap-count faded fuel economy dictated the pace of the field up front, some running slower than others in an effort to save enough to get to the end. Stewart had been running at Truex's pace but once the latter inevitably pitted for fuel, he grabbed the lead with 14 laps left.
Behind him Roush Fenway's Matt Kenseth and reigning champion Jimmie Johnson started to drop back with their fuel-saving tactics, while from behind Richard Childress driver Kevin Harvick went on a charge to try to make the most of having saved fuel earlier in the final stint.
Harvick moved up to second and started to close on Stewart but in the end the leader picked up his pace slightly after overtaking some backmarkers, keeping his rival at bay to claim the third Chicagoland victory of his career and his 40th at Cup level.
"I had a migraine all day yesterday so I am kind of glad we didn't race," said Stewart. "It's nice to finally get one of these this year and I guess if you have to wait to get the first one, it's alright to pick it here.
"We've had a miserable year but the last three weeks we really started coming into it. Going into the race I don't think [crew chief] Darian Grubb and I shared a thought that we would had as good a car as we needed to win."
Harvick had been around Stewart from the early laps as both made their way through the field from their poor starting spots. The RCR driver lamented a poor day in the pits and missing a possible fifth win of the season but still celebrated taking the Chase lead for the first time in his career.
Johnson and Kenseth ran out of fuel on the final lap, handing third to Dale Earnhardt Jr, the best placed of the Hendrick Motorsports drivers both in the race and the Chase. Earnhardt struggled at stages but ran strongly in the final stint - moving up in the order while capitalising on others failing to save enough fuel.
Roush's Edwards was fourth in the end after his team looked to be the pacesetter early on, while Penske's Brad Keselowski finished fifth ahead of his team-mate Kurt Busch. The former struggled with balance initially but following a strategy gamble he was able to move up in the order and secure a strong finish. Meanwhile Busch - who led the most laps - voiced his frustration on his radio over the lack of balance of his car on the last run, but still secured a solid finish.
Kenseth crossed the finish line eighth while pushed by fellow Ford driver Travis Kvapil after his tank ran empty. As the rules state a car cannot be assisted on the final lap he was penalised and pushed down to 21st as the last car on the lead lap.
That promoted Stewart's team-mate Ryan Newman to eighth despite running out of fuel, while Hendrick's Mark Martin and his team-mate Johnson - also out of gas - completed the top 10.
The fuel-saving gamble did not pay off for former Chase leader Kyle Busch, who pitted right before the end and finished 23rd, a lap down.
Similarly Jeff Gordon suffered a blow to his title hopes as he finished 22nd. Tyre and balance issues hampered him early on and after recovering and closing on a top 10 finish he also ran out of fuel.
Denny Hamlin pitted under green in the opening stages with a vibration and dropped a lap down, and later suffered a left-front puncture. An eventual 30th-place finish but puts him out of title contention.
Results - 267 laps: Pos Driver Team/Car Time/Gap 1. Tony Stewart Stewart Haas Chevrolet 2h47m41.000s 2. Kevin Harvick Childress Chevrolet + 0.941s 3. Dale Earnhardt Jr Hendrick Chevrolet + 7.043s 4. Carl Edwards Roush Fenway Ford + 12.579s 5. Brad Keselowski Penske Dodge + 15.649s 6. Kurt Busch Penske Dodge + 16.897s 7. Clint Bowyer Childress Chevrolet + 17.240s 8. Ryan Newman Stewart Haas Chevrolet + 18.477s 9. Mark Martin Hendrick Chevrolet + 19.606s 10. Jimmie Johnson Hendrick Chevrolet + 20.182s 11. David Ragan Roush Fenway Ford + 20.671s 12. Kasey Kahne Red Bull Toyota + 20.930s 13. Brian Vickers Red Bull Toyota + 21.464s 14. Juan Pablo Montoya Earnhardt Ganassi Chevrolet + 22.349s 15. Jeff Burton Childress Chevrolet + 22.717s 16. Joey Logano Gibbs Toyota + 23.242s 17. Regan Smith Furniture Row Chevrolet + 23.456s 18. Martin Truex Jr Waltrip Toyota + 25.025s 19. Marcos Ambrose Petty Ford + 38.038s 20. Paul Menard Childress Chevrolet + 40.161s 21. Matt Kenseth Roush Fenway Ford + 1 lap 22. Kyle Busch Gibbs Toyota + 1 lap 23. Trevor Bayne Wood Brothers Ford + 1 lap 24. Jeff Gordon Hendrick Chevrolet + 2 laps 25. Mike Bliss FAS Lane Ford + 2 laps 26. Greg Biffle Roush Fenway Ford + 2 laps 27. AJ Allmendinger Petty Ford + 2 laps 28. Andy Lally TRG Chevrolet + 2 laps 29. Casey Mears Germain Toyota + 2 laps 30. Landon Cassill Phoenix Chevrolet + 3 laps 31. Denny Hamlin Gibbs Toyota + 3 laps 32. David Reutimann Waltrip Toyota + 4 laps 33. Dave Blaney Baldwin Chevrolet + 4 laps 34. JJ Yeley Front Row Ford + 4 laps 35. Scott Speed Whitney Ford + 7 laps 36. David Gilliland Front Row Ford + 8 laps 37. Bobby Labonte JTG Daugherty Toyota + 31 laps Retirements: Jamie McMurray Earnhardt Ganassi Chevrolet 163 laps Robby Gordon Gordon Dodge 77 laps Joe Nemechek NEMCO Toyota 45 laps David Stremme Inception Chevrolet 44 laps Josh Wise Max Q Ford 41 laps Michael McDowell HP Toyota 25 laps
