The 59-year-old Lehman closed with his second straight 7-under 65 for a one-stroke victory over Toms.
"As a competitor, you don't want to win that way. Honestly, you don't," Lehman said. "You love winning. I'm not going to give the trophy back, but you would rather make a putt than have somebody miss a putt. So I felt bad for him because I thought he played extremely well."
Four strokes ahead of Lehman entering the round, Toms finished with a 70. His long first putt on the par-4 18th went 7 feet past, and he missed the comebacker to hand Lehman his 12th victory on the 50-and-over tour.
"Hate to end up that way on the last hole," Toms said. "Trying to make it (the first putt) because I figured if I made it, I had a chance to win right there. Never even entered my mind that I was going to three-putt."
Lehman finished at 17-under 199 at windy Hualalai. He birdied Nos. 13, 14 and 16 and closed with two pars.
"I like the fact that the wind was blowing," Lehman said. "I always feel like when the wind blows, my chances get better. Historically, I've always been a real steady ball striker, and when the wind blows, that's what you really have to do."
Toms made seven straight pars before the finishing bogey.
"Hit a lot of good putts on the back nine that I didn't make, and Tom played great," Toms said. "I told you yesterday standing right here somebody was going to play good today and I had to play really well. I shot 16-under par for the tournament in some pretty tough wind. I felt I played solid."