'Nervous' Shiffrin equals women's World Cup victory record
The 27-year-old American produced two stunning runs to beat the Italian Federica Brignone by 0.77 seconds. The Swiss Lara Gut-Behrami was third, 0.97sec beind Shiffrin.
"I was a little nervous because of the record," Shiffrin told broadcaster Eurosport.
"I wanted to ski well and I did it. I can't believe it.
"It was pretty amazing conditions. I got reports from the coaches that everything is fully attackable and today I wanted to fight for it."
Shiffrin, who could only finish sixth in Saturday's first giant slalom, is now just four wins shy of matching the overall record of 86 wins held by the Swedish legend Ingemar Stenmark, who dominated the men's slalom and giant slalom disciplines for a decade from 1975 before retiring in 1989.