Toronto, Canada – By Mark Meadows
Germany's Maria Riesch led with 21 skiers already down and Vonn was level with her main rival at the first intermediate checkpoint.
Some tight turns meant she fell slightly behind halfway down before making up the time in the final section.
The overall World Cup leader crossed the line in one minute 37.70 seconds, beating Riesch into second by 0.42 seconds.
"It's been amazing, a great weekend. I love racing at Cortina. Things couldn't have gone better," a smiling Vonn told reporters with one eye on Sunday's giant slalom.
"I feel really strong right now. I'm skiing with confidence and I always attack."
Swede Anja Paerson and Switzerland's Nadja Kamer finished joint-third after going all out in their runs.
The picturesque Olympia delle Tofane piste, which snakes its way through the jagged peaks high above Italy's most exclusive ski resort, was bathed in sunshine and offered perfect skiing conditions.
Vonn took full advantage with her immense speed still baffling pundits given her relaxed skiing style.
"It's really annoying," said Riesch, second in the overall standings.
"I am very upset because again I have missed an opportunity. It's demoralizing for me that Lindsey is always above me and I hope that eventually someone else wins, although I'm still friendly with her."
The vastly experienced Paerson, also third in Friday's Super-G and now fourth in the overall World Cup, wanted to concentrate on her form rather than worry about Vonn's domination.
"It shows you are human. No one likes their job every day."
(Additional reporting by Manuele Lang; Editing by Alison Wildey)