Singh closed with a 6-under-par 65 for a total of 16-under 268. He had six birdies in a bogey-free final round that was held over a day after darkness suspended play Sunday night.
Chris Riley (71), J.L. Lewis (71) and Jonathan Byrd (68) shared second at 12-under 272.
The $630,000 first prize boosted Singh's earnings for the year to more than $5.6 million, edging him past Davis Love III. Love, nursing a sore back, finished tied for 27th at the Quad City PGA stop.
Singh, in his first Deere Classic appearance, also is in the running for player of the year honors, But he said the money list is more important to him.
'I can control the money list. I can't control the player of the year,' said Singh, adding that Masters champion Mike Weir would top his list for that award.
With three more tournaments ahead, Singh said this year might be his best shot at topping the money list.
'If I play well, I just have no worries about what can go wrong,' said Singh, who now has won 14 career PGA events.
Riley called Singh a world-class player who's hard to catch when he has a weekend lead.
'He's in there with Tiger Woods, Davis Love, Mike Weir -- he's in their class. I'm trying to get there,' said Riley, who won the 2002 Reno-Tahoe open and now has six top 100 finishes this year.
Singh started play Monday at 12 under, tied with Lewis, who posted his lone career win at the Deere Classic in 1999.
The pair resumed their final round Monday on No. 6, and Singh began to pull away after he birdied No. 8 and Lewis followed with a bogey on No. 9.
Lewis, who used only 50 putts when he shot consecutive 6-under 65s in the first two rounds, struggled on the green over the weekend.
Paul Stankowski, in his third PGA event since returning from wrist surgery, tied for fifth at 11 under with Hidemichi Tanaka and Kevin Sutherland.
The Deere Classic drew its best field after being moved back from its usual tee off in July. However, the tournament was plagued by a Saturday downpour that postponed Saturday's third round.
Tournament officials had hoped to wedge in 36 holes on Sunday so players could travel to the next stop, the 84 Lumber Classic in Pennsylvania.
But a storm front that dumped more than 3 inches of rain Friday and Saturday lingered over the Quad Cities, pushing tee times back until late morning.
The Deere Classic is the first PGA Tour event to extend into Monday since the FBR Capital Open in June. However, 22 of 39 tournaments this year have had some kind of weather delay.
Copyright 2003 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.