'I'm really happy to take over the money list,' said Singh, who has won two of his last three events on tour. 'I'm playing the best that I can play right now. And that's a good feeling to go out there knowing that you've got a chance of winning the golf tournament every time you tee it up.'
Tiger Woods, who falls back to second in the race for the money title, fired a 7-under 65 to join Scott Verplank and Stewart Cink in a tie for second at 19-under-par 269. Woods has played in eight fewer events this year than Singh.
Singh, who has now put himself in position to end Woods' streak of money titles, was part of a four-way tie for the lead after three low-scoring rounds on the Magnolia and Palm courses at Walt Disney World Resort.
'I'm in the best position to win the money title,' said Singh. 'I'm going to go out there and try to do the best I can and have a good, strong finish.'
He played in the penultimate group off the first tee at Magnolia and found himself in a battle with Cink after both players tallied a pair of birdies each over the first six holes.
Singh grabbed the lead with a birdie at the eighth and opened a two-shot advantage with a birdie at the 10th.
He reached 23 under with a long birdie at the 12th before finding trouble with a bogey at the very next hole. Singh recovered immediately and knocked a sand- wedge inside four feet for a birdie at the 14th to take a four-shot lead over the field.
Singh dropped another shot with a bogey at the 16th but his victory was never in doubt.
The 40-year-old closed in style with a 35-footer for birdie at the last to secure this 15th career title on the PGA Tour.
'I feel like if I win the money title, I have a good chance of winning Player of the Year,' said Singh. 'But the players have to decide that. It's a matter of time to see what happens in the next two weeks.'
Woods was six shots off the pace to start the day and struggled early with a bogey at the first to fall further back but in vintage fashion, the top player in the game roared back.
He collected three birdies on the front side to make the turn at 14 under and reached the green in two for an eagle at the par-5 10th.
Woods kept cruising up the leaderboard with back-to-back birdies from the 13th and added a birdie at the 17th for his share of second.
The 27-year-old is within reach of regaining the lead in the race of the money title, but with Singh playing next week at the Chrysler Championship the Fijian seems to have the upper hand.
'If he has it wrapped up, so be it,' said Woods. 'Anybody would rather have Player of the Year than the money title.'
Cink used three birdies and two bogeys to shoot a 71 and earn his first top-10 finish since June.
'I'm disappointed because all week I played well and trying to win, and today I just couldn't seem to put it together,' said Cink. 'Second is good, but I felt like I could have played with a lot more pressure today.'
Davis Love III, who like Singh has won four times on the PGA Tour this year, posted a final-round 69 to share fifth place with John Rollins at 18-under-par 270. Michael Clark II and Bob Estes were one shot further back at 17-under-par 271.
Bob Tway, Rocco Mediate and Geoff Ogilvy tied for ninth at 16-under-par 272.
U.S. Open winner Jim Furyk shot a 65 to join Tom Carter, Brent Schwarzrock, Fred Couples and David Peoples at 15-under-par 273.