The Dane had four birdies and no bogeys in finishing at 9-under 275 at Celtic Manor. Niclas Fasth of Sweden birdied the last for a 5-under 66 to take second place and Ignacio Garrido (69) of Spain was another shot back in third.
I am so surprised at winning, Huldahl said. I was so nervous on the last three holes, I couldnt feel my hands. Playing 18 was a very emotional experience.
The 26-year-old Huldahl moved to the European Tour this year after three years on the satellite Challenge Tour.
Gary Lockerbie, after a weeks best 65, and fellow Englishman Danny Willett (67) shared fourth place at 278.
Colin Montgomerie, Europes Ryder Cup captain, closed with a 71 for 287 and tied for 37th. Rival U.S. captain Corey Pavin had a 73 for 288 and tied 43rd.
Fasth holed a 70-yard lob wedge for an eagle at the 11th.
I wasnt playing great but the putting came around after I changed to a new putter this week, he said.
He was right in the hunt at that point, but bogeys at Nos. 16-17 cost him his chance.
Normally if Im comfortable I dont screw up like that, but I am not quite there yet. I havent been really comfortable all week, said Fasth, a former Ryder Cup player.
Halfway leader Richie Ramsay of Scotland, the 2006 U.S. Amateur champion, escaped a possible two-shot penalty over concern he had broken a rule during the rain-disrupted third round Saturday.
Ramsay was questioned for nearly two hours Saturday night about an incident on the eighth hole, where he was seen on television pressing the ground behind his ball before playing a shot. In the end, no penalty was imposed.
But the Scot did incur a one-stroke penalty for an infraction on the final hole Sunday morning, when he completed the last two holes of his third round, both of which he bogeyed to complete a 5-over 76.
He then shot 69 in the final round to tie for 10th.