Following her second place in Saturday's downhill on the Mont Lachaux slopes, the Sochi 2014 bronze medallist clocked 1:15.63, finishing 0.93 seconds ahead of Austria's Tamara Tippler.
That was the biggest winning margin in a women's super G since 2015 (1.32 seconds, Lindsey Vonn in Lake Louise).
Overall World Cup holder Federica Brignone was third, 1.02 seconds behind Gut-Behrami, clinching her ninth Super G podium.
The 29-year-old from Canton Ticino won her third Super G on home snow after St. Moritz in 2008 and Lenzerheide in 2014, and now tops the discipline's rankings with 245 points, overtaking teammate Corinne Suter (ninth today).
With 14 Super G wins, the Swiss skier is fourth on the women's all-time list led by Lindsey Vonn (28).
On the fast course set by the Italian coach Giovanni Feltrin, six women failed to finish.
Among them was Olympic downhill champion Sofia Goggia, who had won two consecutive downhill races on the same track; the Italian missed the penultimate gate while on course for a spot on the podium.
Starting with bib number 1 Petra Vlhova made a mistake over a jump and didn't finish. The Slovakian still leads the overall standings with 861 points ahead of Switzerland's Michelle Gisin (743).
Next stop in the women's calendar is the giant slalom on Tuesday 26 January in Kronplatz, Italy, with the speed events returning in Garmisch-Partenkirchen, Germany, next weekend.