Nobilo, three strokes behind with five holes to play, charged into the lead with three consecutive birdies starting at the 14th hole.
Even a bogey at the final hole, where he took three putts, did not matter in the end as the European Tour stalwart held on to record his first victory on American soil.
"It's lovely to win in America. I was just thinking the other night that I've won everywhere except Japan and America," Nobilo said after a closing four-under-par 68.
The New Zealander finished with an eight-under 208 in the rain-shortened event, while the second-round leader Jimenez (73) and Zimbabwe's Mark McNulty (67) tied for second on 209.
Nobilo collected pounds 235,000, the biggest payday of his career, for his second victory of the year. He won the European Tour's BMW International Open in Munich in July. "This is almost what I won in Europe the entire year," said Nobilo, 35, who has been struggling recently while working on a swing change.
His victory completed a great weekend for New Zealand golf, coming only hours after his compatriot Michael Campbell won the Alfred Dunhill Masters in Indonesia. Nobilo and Campbell will team up to represent New Zealand in the World Cup of golf in Shenzhen, China, starting on Thursday.
Jimenez fell behind with bogeys at the 15th, where he three-putted, and the 17th, where he made a mess of a chip, and missed a 20-foot birdie chance at the final hole which would have put him into a play-off.
Sam Torrance, of Scotland, who was alongside Nobilo overnight at four strokes off the lead, could only manage a final-round 74 to finish on 214, the same total as Paul Curry, of England, who finished with a 70.
Nobilo's presence in Shenzhen will be a boost for the first major professional tournament in China, which yesterday lost Ian Woosnam. He withdrew after reportedly telling his Welsh team-mate, Mark Mouland: "You're better off without me."
Rather than flying on from Indonesia, where he shot a closing 77 in the Alfred Dunhill Masters , the former world No 1 asked to be booked on the next available plane back to Britain where he will see a specialist after a recurrence of back trouble.
Phillip Price, 110th on this season's European money list, has agreed to stand in at short notice, although Mouland, who finished joint second in Indonesia, said: "There won't be much time for him to acclimatise and get used to the time difference."
Woosnam was only five strokes off the lead in Jakarta with a round to go, but had already voiced his intense dislike of the humid conditions which made coping with his injury more difficult. On the final day he slumped 17 shots behind the winner.
Barry Lane shot a third successive 69 but had to settle for joint second place at the Kapalua International tournament in Hawaii. The 35-year-old Middlesex player was tied with the Americans Russ Cochran and Jim McGovern on a 17-under- par total of 273 - two strokes behind Jim Furyk, who finished with a 70 for a tournament record total.Reuse content