Three strokes clear overnight, the world number one fired a one-under-par 69 for an eight-under total of 272, finishing ahead of fellow American Woody Austin (67) at a sun-baked Southern Hills Country Club.
South African Ernie Els birdied four of the first 10 holes on his way to a six-birdie 66 and third place at five under.
Woods, who claimed his 59th PGA Tour title, became only the third player to win at least four PGA Championships. Fellow Americans Jack Nicklaus and Walter Hagen won five apiece.
"Any time you win a major championship in the year it's always going to be a great year, and this certainly is," a smiling Woods told reporters, having gone on to win his 13th major after holding at least a share of the 54-hole lead.
"And it's a feeling I've never had before, having Sam there and having Elin there," he added, referring to his wife and two-month-old daughter Sam Alexis who were waiting for him in the scorer's hut.
"This one feels so much more special than the other majors."
Woods, whose last major victory came in the 2006 PGA Championship at Medinah, said he gave himself a wake-up call after bogeying the ninth and 14th holes.
LOSING MOMENTUM
"I felt like I gave all the momentum back to Ernie and to Woody," the 31-year-old said. "I made a mess of it there on 14 and I just did serious yelling at myself going up to the 15th tee, just to get back into what I do.
"When I made that putt there on 15, it felt great. I felt like I had the momentum again and I was back in control of the tournament."
Overwhelming favourite at the start of another stifling day, Woods briefly stretched his lead to five when he rolled in a curling 25-footer from the fringe at the par-three eighth.
As the ball dropped into the hole, he pumped his fist in celebration.
However, he then bogeyed the uphill ninth to reach the turn in one-under 34 and also faltered at the par-three 14th, where he three-putted
At that point, his lead had been trimmed to one with Austin and Els his closest challengers.
With typical timing, though, Woods hit back with a birdie at the par-four 15th, calmly rolling in a 12-footer to restore his two-stroke cushion. He safely parred the last three holes to ensure he ended another year with at least one major title.
After his ball dropped into the cup, the game's leading player removed his cap and lifted both arms into the air to acknowledge the roars from the crowd packed around the green.
FIGHTING TIGER
Austin, who booked a place in the U.S. Presidents Cup team with his first top-10 finish in a major, was delighted Woods was given a bit of a fight in the final round.
"I think it's great that Ernie and I didn't let him just coast in," the 43-year-old former bank teller said. "I'm going to take this as far as I can take it and try to be as positive about it as I can and hopefully turn the corner."
Three-times major winner Els rued a few missed putts after posting his fourth top-five finish in the PGA Championship.
"I played really well today and got off to the start I needed," the 37-year-old said.
"I made a lot of putts but I missed one on nine and one on 11, plus the drive on 16, and that probably cost me.
"If I could have those three back, it would have been a perfect round of golf. But I played really nice and at least I had half a go at it."
Canadian Stephen Ames, who played with Woods in the final pairing after lying second overnight, fell back into a tie for 12th at two over after closing with a 76.
Temperatures reached 102 degrees (39 degrees Celsius) in the final round, with a heat index of around 110 making it one of the hottest days in major championship history.