Hoefl-Riesch flew down the course in 55.04 seconds in her second run, giving her a combined time of 1 minute, 55.58 seconds.
Tanja Poutianen came in second and American teenager Mikaela Shiffrin placed a surprising third with a 1:56.32.
It was the second slalom podium for 17-year-old Shiffrin in just a dozen starts.
She finished the first run in third place and held on despite sometimes tricky lighting on the course, which is above the Arctic Circle.
"I felt confident because I had a plan to just ski like I do in training and I knew I could do that," Shiffrin said. "I wasn't worried about what place I was going to come in."
The U.S. team made the long trip to Levi without stars Lindsay Vonn and Julie Mancuso, who opted to remain in the United States to train for the Nature Valley Aspen Winternational, taking place Nov. 24-25 in Colorado.