Karlsson finished at 15-under 273, three strokes ahead of 2009 Qatar champion Alvaro Quiros, who moved from sixth to second Sunday with a 5-under 67 that included a closing run of three consecutive birdies. Brett Rumford and Lee Westwood tied for third at 11-under.
Third-round leaders Bradley Dredge and Paul Casey sagged with final-round 2-over 74s and ended up tied with Oliver Wilson for fifth at 8-under.
Karlsson moved into contention with three birdies over a four-hole span from Nos. 5-8. While the leaders were faltering, Karlsson took advantage with birdies at 11 and 14 for the lead. He sealed the victory with birdies at 17 and 18.
It was the 10th European PGA Tour title for Karlsson, a 21-year pro from Sweden, but first since October 2008. He missed the second half of the 2009 season after an injury left him without depth perception in his left eye.