The American clocked one minute 36.48 seconds to beat Liechtenstein's Tina Weirather for her 40th World Cup downhill win, with another young American Jacqueline Wiles in third for her second career podium spot.
Oregon's Jackie Wiles joined Vonn on the podium in third, replacing EagleVail's Mikaela Shiffrin from a day earlier.
Slalom specialist Shiffrin, 22, has won 10 times this season, including five in a row since January 1, to edge to 41 World Cup victories overall.
"It wasn't like I made a big mistake", Vonn told reporters in the finish.
Vonn stands eight victories shy of the career wins record held by Sweden's Ingemar Stenmark (86), and she nearly certainly would have pulled closer Friday if not for the rut which deflected her right ski upward with the tip rising to the level of her waist.
It continued a strong weekend for the American who was second in Friday's first downhill behind Italian Sofia Goggia - the latter failed to finish on Saturday.
Lindsey Vonn proved that age is just a number with a record-breaking FIS World Cup win in Saturday's downhill race in Italy. She missed the Sochi Winter Olympics with a knee issue. "I don't know how South Korea is going to go but it's a really good sign". "So it made me really happy just to be out there on the mountain today".
Wiles was skiing just off Vonn's pace at the top intervals but almost overcooked a turn after catching a rut. She has now won back-to-back downhills this season. "I really don't give a s- about that stuff". "A little scary at the bottom, but I kept is rolling and it came together".
The podium was instead completed by Vonn's compatriot Jackie Wiles who became the fifth U.S. female alpine skier to qualify for the Olympic Games. "For me, February is the most important thing".
"She has done a lot to help me get to this point", Wiles said of Vonn. I've been skiing with her since we were like 9 years old.
While Vonn has struggled, USA starlet Shiffrin has become the preeminent skier on the world stage.
Goggia still leads the downhill ranks, seven points ahead of Weirather and 13 ahead of Shiffrin. Vonn and Shiffrin have also qualified for the Olympics in super-G, and Shiffrin has qualified in giant slalom and slalom, too. "I think I'm skiing better super-G than downhill".