While winning a European Tour tournament for the second time in his career, Hanson became the first Swedish player to win this event since Jesper Parnevik in 1998.
He outlasted his nearest challengers by overcoming Sunday's dismal cold, wet and windy conditions.
"What a day," he said. "If my chiropractor had been here he might have told me to pull out, so I'm glad he wasn't. After all I've been through I was going to finish no matter what. It's been a long wait for me."
Gary Orr (71), Sam Walker (69) and Paul Broadhurst (68) finished 7-under 273, good for a three-way tie for fourth place.