He started with a one-shot lead and before he could reach the turn, Langer fell as many as four shots behind. He rallied to take the lead, only to block a tee shot toward the trees on the final hole, catch a small break because a TV structure was in his way, and scramble for par.
It ended with Langer knocking in a par putt just inside 4 feet for a 2-under 70 and a one-shot victory in the Insperity Invitational.
"I was very, very fortunate in the end to pull this off," the 60-year-old Langer said. "I've got a lot more gray hair right now."
Langer won for the 37th time on PGA TOUR Champions -- only Hale Irwin with 45 victories has more -- and for the fourth time at the Insperity Invitational.
Paul Goydos led for much of the back nine. He dropped two shots over the final five holes, including a bogey on the 18th that gave him a 68. He tied for second with Jeff Maggert and Bart Bryant, who each had a 69.
"I'm always surprised when I play well, especially this week," said Goydos, who had not finished higher than 24th this season. "I had no inclination that I was going to be remotely competitive. But I probably made the most birdies of anybody (for the week) but also, as it turned out, too many bogeys."
Goydos was right. He led the field with 19 birdies.
Langer finished at 11-under 205 and won $330,000 to move to the top of the Charles Schwab Cup standings for the first time all year.
He was 2 over for the final round through eight holes at the The Woodlands Country Club and at one point noticed that Goydos was starting to pull away. Langer made a key birdie at No. 9, added one to start the back nine and then made birdie on both par 5s.
"I figured I needed 12 under to have a chance. I was fortunate that 11 under did it," Langer said.
He last won in the penultimate Schwab Cup playoff event last year. Not only did he go the first four months without winning, Langer was out of the top 15 in four out of five starts earlier in the season.
He was getting closer, losing in playoffs each of last two PGA TOUR Champions events.
"I didn't want to do three playoffs in a row here," he said.