In making Friday's podium behind Norway's Ragnhild Mowinckel and Germany's Viktoria Rebensburg Shiffrin moved into an unassailable lead in the overall standings. Gallhuber's compatriot Bernadette Schild finished third, 0.39 seconds behind the leader.
Her nearest rival, Wendy Holdener of Switzerland, lost any hope of overhauling the U.S. star when she trailed in 14th on Friday.
The result comes after Shiffrin took the overall World Cup title finishing third in the giant slalom on Friday, and an Olympic gold medal for Team USA in the same event last month at PyeongChang.
Shiffrin had not raced since the Olympics.
Shiffrin was guaranteed of winning the title because her only remaining rival, Wendy Holdener, failed to finish in the top two, ESPN reported.
Vonn, who did not compete in the Ofterschwang tech events, is trying to pad her overall women's record of 81 career World Cup wins as she's chases the all-time mark of 86 held by Sweden's Ingemar Stenmark.
Shiffrin, 22, now has a 603-point lead heading into next week's World Cup finals with five races left before the end of the season and she also has a good chance at clinching the overall World Cup slalom title Saturday if she finishes 10th or better in Ofterschwang. Her last race was at age 26.
Her 11th win of the season ties her mark from previous year and is the third most ever on the women's circuit behind Vail's Lindsey Vonn, who won 12 races during the 2011-12 season and retired great Vreni Schneider of Switzerland who won a record 14 races during the 1988-89 season. Two more races remain for her at the World Cup finals next weekend at Are, Sweden.
Thomas Dressen of Germany won the men's downhill race today in the Norwegian resort of Kvitfjell.