Fenninger won with a combined time of two minutes, 27.03 seconds. The Austrian won silver in the GS at the Sochi Olympics, and won gold in the super-G.
Anémone Marmottan of France was 0.23 seconds back for her first ever World Cup podium appearance.
Lara Gut of Switzerland and Eva-Marie Brum of Austria were tied for third.
Olympic giant slalom champion Tina Maze of Slovenia led after the first run but slipped to fifth place.
Marie-Michèle Gagnon was the top Canadian. The Lac-Etchemin, Que., native was 13th.
Marie-Pier Prefontaine of Sainte-Agathe-des-Monts, Que., did not qualify for the first run, while Brit Phelan of Mont-Tremblant, Que., did not finish the first run.
In other notable results, discipline standings leader Jessica Lindell-Vikarby of Sweden was sixth, while American teen Mikaela Shiffrin was 15th.
Fenninger closed the gap in the overall World Cup standings, now just 67 back of Germany's Maria Hoefl-Riesch, who finished 21st.
Fenninger's 64 points back of Lindell-Vikarby in the giant slalom standings.
There are six races remaining in the season, with two more scheduled in Are this weekend.