Rich Beem, the PGA Champion, finished alone in fourth place at 1-over-par 145.
Woods's 61 broke the old course record of 65 at Poipu Bay Resort Golf Course. Ernie Els first shot the 65 in 1997 before Woods matched it last year. The 61 also set a new 18-hole record for the PGA Grand Slam of Golf, besting Tom Kite's score from PGA West in 1992 by a single stroke.
The 36-hole total of 127 broke Woods' record from last season by five shots.
'I was surprised at a couple shots I hit out there,' said Woods, whose 61 matched his lowest 18-hole tournament round. 'I really couldn't mis-hit a shot today. Every shot I hit was right in the middle of the face.
'I was making shots, aiming at my shots and I was knocking down my putts,' he said. 'It's a lot of fun when everything works like that.'
Love shot a 3-under 69 on Wednesday, while Leonard carded an even-par 72 to tie at 3-under-par 141. Beem posted a final-round, 1-over 73 to finish the 36-hole event at 1-over-par 145.
'What a phenomenal round Tiger played, and it was a lot of fun watching him,' Beem said. 'It's amazing how when somebody gets on a roll like he got on today, how fun it is to watch somebody, because everything clicks. The golf ball was just going right at the target all day.'
Woods held a three-shot lead at the start of Wednesday's final round and wasted little time in extending his advantage. He collected a pair of birdies in his first two holes then parred three and four.
His play over the next four holes put the tournament out of reach and turned it into an exhibition of the greatness of the top player in the game. Woods birdied the next four holes in a row to shoot a front-nine, 6-under 30.
'I needed to go out there and play a good, solid front nine and I just got on a roll,' said Woods, the PGA Tour's leading money winner in 2002. 'It just kept going.'
Woods kept it going on the back nine. He drained a 20-foot birdie putt at No. 12 and made it two in a row with a three-footer at the par-4 13th. He parred the par-5 14th but once again carded back-to-back birdies at the 15th and 16th.
He missed a 35-foot birdie try at the par-3 17th but two-putted for birdie from 45 feet at the closing hole to polish off the blow out and post his 61.
With the exception of winning the WGC-Match Play Championship, maybe the only thing missing from Woods' amazing resume is the elusive 59. The No. 1 golfer in the world claimed to have never thought about it Wednesday.
'I never thought about it,' said Woods. 'I just thought about playing it one shot at a time. When you start going low like that, you don't really think of numbers like that. You just get into the rhythm of the round.'
Leonard, who was alone in second after the first round never found that rhythm on Wednesday. His 72 included two birdies and two bogeys and several missed opportunities.
'I love Kauai, don't get me wrong, but I'm glad I'm not playing the golf course again tomorrow,' Leonard said. 'That doesn't mean I don't want to come back, and I hope to next year.'
Leonard took a fourth in his only other appearance in the PGA Grand Slam of Golf back in 1997. That was the same year Woods made his debut and Love was also in the field that year after winning the PGA Championship.
This event normally features the four major winners from 2002 but with Woods capturing The Masters and The U.S. Open and with British Open champion Ernie Els electing not to play, Leonard and Love were added to the field. Leonard is No. 1 on the major champions points list with 253.5 points while Love finished third with 188.5 points. Retief Goosen was second but like his fellow countryman Els, he could not play due to a scheduling conflict.
Love had it going on Wednesday with four birdies through 15 holes but ran into trouble at the par-5 16th. He landed in a lateral hazard and two-putted from 12 feet for bogey.
'I didn't play very well today again,' said Love, who shot an even-par 72 on Tuesday. 'I enjoyed watching Tiger's round. It was one of the better rounds I've seen in a long time.'
Beem started out with two birdies in his first two holes but a 7-iron into the water at the seventh thwarted his chances of making a move.
Woods won $400,000 for the victory while Leonard and Love each pocketed $225,000. Beem left with $150,000 for his fourth-place showing.