'I'm absolutely delighted,' said Dougherty. 'When you're playing with Colin (Montgomerie) and Thomas (Bjorn) you really don't think it's over until it's over. Hopefully this is the start of many great things to come.'
Montgomerie, the 2004 champion, bogeyed the final hole to finish at 13-under- par 275 after a final-round 70. He was joined in a tie for second by Maarten Lafeber, who posted a 69 on Sunday. Bjorn carded an even-par 72 in the final round to take fourth place at minus-11.
Dougherty, playing with two-time Ryder Cup teammates Montgomerie and Bjorn, never blinked on Sunday. He was steady at the start with seven consecutive pars despite Montgomerie tying him in the lead after birdies at Nos. 3 and 5.
The 22-year-old then birdied the par-3 eighth for the third time in the tournament to move one clear of the Scotsman. Dougherty birdied the par-5 11th for the third straight day to move to minus-15 and a two-stroke cushion.
After Montgomerie birdied the 13th to get within one stroke, Dougherty birdied No. 14 to regain a two-shot lead. Monty kept pace with his fourth birdie in four days at the 15th.
Dougherty's lead moved to three as he birdied at the par-4 16th. He had pulled his drive left on 16, but received a favorable ruling allowing him to take a free drop. Meanwhile, Montgomerie three-putted the same hole for bogey to drop three back.
The Englishman closed out a bogey-free round and his first professional win with a birdie at the par-4 18th on the Masters Course at Laguna National Golf & Country Club.
Montgomerie, who won by three strokes in 2004, also stumbled to a bogey at the last to finish five strokes behind Dougherty.
'It was an impressive effort from Nick and he deserves his win and all good luck to him,' Montgomerie said. 'It was never going to be my day and when the ruling happened on the 16th, I knew that was going to be the case.'
Lafeber tripped to a bogey at the first hole. For the second straight day, he carded three birdies in a four-hole stretch from the fourth to move to 12 under.
The 2003 Dutch Open winner faltered to a double bogey at the par-4 ninth. He got one stroke back with a birdie at the 13th. Lafeber managed to gain a share of second place as he closed with back-to-back birdies to end at minus-13.
Peter Lawrie (66) and Lee Westwood (67), a 16-time winner on the European Tour, led a group of players that shared fifth place at 8-under-par 280. They were joined there by Robert Coles, Marcus Fraser, Gregory Havret and Wen-Chong Liang.
Peter Hedblom struggled to a final-round, 3-over 75 to finish at minus-7. Joong Kyung Mo (70) and Peter Senior (69) finished one stroke further back at 6-under-par 282.