Vonn's winning time was 1:36.70, well ahead of Anja Paerson of Sweden at 1:37.53. Canadian Emily Brydon was third.
"It was awesome," Vonn said. "I really had fast skis today."
The American's victory put her one behind former stars Picabo Street and Daron Rahlves in all-time U.S. World Cup downhill titles.
Vonn has won 11 cup races in her career, including two super-Gs and a super combined.