After three consecutive second-place finishes, Weirather finally climbed to top spot of the medal rostrum after recording a time of 1:17.38 minutes in near-perfect race conditions.
Sweden's Kajsa Kling was second in 1:17.69 while Anna Fenninger picked up the bronze for Austria in 1:17.77 minutes.
The win takes Weirather's total of podium finishes this season in all disciplines to five, the most of any on the women's tour this season.
While the 24-year-old also joins her mother Hanni Wenzel and Ursula Konzett as the only women from Liechtenstein to win multiple World Cup events, following her first career victory in the Super-G event in Garmisch-Partenkirchen last March.
But she remains second in the overall standings this season, trailing Lara Gut, a seventh-place finisher in Switzerland, by 37 points.