Noren finished at 20-under 264 to hold off 2006 winner Dredge, who shot a 65.
Ross McGowan had a 65 to finish third at 267, two ahead of Miguel Angel Jimenez (67).
Noren was pleased he held on to his third-round lead after losing from a similar position at a tournament in Portugal in 2007.
“I learned from that because then I thought I had better win because I’m leading. But today I said to myself ‘a lot of guys can shoot low rounds so I had better shoot one myself,”’ the Swede said.
The 27-year-old Stockholm native moved to 38th in the Race to Dubai standings.
Charl Schwartzel, second overnight, three-putted the first two holes for bogeys – as Noren birdied both – and never recovered. He went on to shoot 71 for sixth place.
Rory McIlroy, tied for 34th overnight, shared seventh after a closing 64.
Dredge birdied the first and eagled the ninth holes with seven pars in between. He birdied the next two but a bogey on 12 proved costly.
Noren made a key birdie putt from 20 feet at No. 10 and added a birdie on the long 14th before he pitched in from a greenside bunker for his eagle at 15.
“I was relying on him to make mistakes over the last three, but he played great and congratulations to him,” Dredge said. “Second is better than third, but nothing feels like winning. I did everything I could but it wasn’t enough.”
Thongchai Jaidee had a 67 to finish at 270, good for fifth place in the event co-sanctioned for the first time by the Asian Tour.
McIlroy said Saturday he would aim for a possible top-5 finish and had a share of third when he made his fourth birdie in five holes at No. 17.
But McIlroy was distracted by a photographer at No. 18 and cut his drive down a slope. The 20-year-old Irishman had to play out sideways to the fairway and ended up with a bogey.
“I holed a lot more putts than I did the last three days, but I probably walked off a little disappointed. I had three bogeys so it could have been a little better,” said McIlroy, who lost a playoff for the title last year.”
Lee Westwood had his best round of the week, a 5-under 66 for a share of 23rd place.
McIlroy and Westwood remained third and fourth in the Race to Dubai, behind Martin Kaymer and Paul Casey, who are both injured.