A race that was Johnson's to lose ultimately became Kenseth's series-high fourth victory of the season and third on a 1.5-mile track after crew chief Jason Ratcliff passed on putting new tires on the No. 20 Toyota following the race's ninth caution.
"I thought he was slightly crazy when that happened," said Kenseth, who widened his lead when the field went four-wide after the restart on lap 246 and saw Johnson's No. 48 Chevy spin from second place on a day he led three times for 182 of 267 laps.
"I didn't think there was any way that we were going to hold on for that win. He made the right call at the right time and those guys got it done."
Kenseth led twice for 38 laps, including the final 23. Johnson, the five-time champion and series points leader, finished ninth and leads Carl Edwards by 38 points.
The restart bothered Johnson, who accused Kenseth of breaking the pace car speed. But Johnson took solace in salvaging his 11th top-10 despite between sandwiched in the logjam that could have been worse.
"We were kind of in an awkward situation in that restart there," he said. "We were like three- and four-wide going in the corner, then something happened with the air and just kind of turned me around. Unfortunate, but at least we rallied back for a good finish."
Second was Jamie McMurray in a Chevy, followed by Clint Bowyer (Toyota), Joey Logano (Ford) and Kyle Busch (Toyota).
Rain on Saturday night forced NASCAR officials to postpone the race to a daytime start.
The event was red-flagged for 18 minutes following a seven-car wreck involving defending race and Sprint Cup winner Brad Keselowski, who returned to finish 33rd. It was the biggest incident of 10 cautions for 42 laps, but things were clean after Johnson brought out the final yellow flag.
Sprint Cup standings
Driver Pts Beh
1. J. Johnson 610
2. C. Edwards 572 -38
3. C. Bowyer 569 -41
4. K. Harvick 544 -66
5. M. Kenseth 528 -82
6. D. Earnhardt Jr. 512 -98
7. Kyle Busch 500 -110
8. M. Truex Jr. 490 -120
9. G. Biffle 489 -121
10. J. Logano 479 -131
11. K. Kahne 478 -132
11. J. Gordon 477 -133