Vonn finished 0.24 of a second ahead of second-place finisher Elisabeth Goergl and 0.30 of a second ahead of Nicole Hosp, who was third.
"It's incredible after being out with two knee operations it is just amazing to be sitting where I am today," Vonn told reporters. "I'm so proud and happy and I really have to thank the people that supported me and got me back to where I am now."
With her seventh downhill title, she has tied former Austrian skiing great Annemarie Moser-Pröll for most downhill World Cup titles by a woman.
Vonn, 30, broke the previous record for World Cup wins in January when she recorded her 63rd win in a super-G race in Italy. Her downhill triumph Wednesday gives her 66 career victories.
Vonn finished 103 points ahead of second-place Anna Fenninger in the World Cup title race. Despite her downhill title, Vonn is no longer in contention for the overall women's World Cup title. She is a four-time overall champion.
Knee injuries nearly derailed Vonn's career. She blew out her knee in a super-G race at the 2013 world championships in Austria. She then suffered another injury to the same knee last year, forcing her to miss the Sochi Winter Olympics.
After going nearly two years without a victory, Vonn won the downhill in Lake Louise, Canada, in December.
"I'm incredibly thankful to be holding another downhill title," said Vonn, who won gold in the downhill at the 2010 Vancouver Olympic Games. "It's been a long two years coming back from my injuries."