Despite a wobble near the top section of the 1.7-mile Oreiller-Killy course, Vonn finished in a time of 1 minute, 51.42 seconds.
"I love Val d'Isere, I've always had a good feeling here. It's great to have another victory," said Vonn, who a downhill-Super-G world championship double and World Cup super combined race last year.
She also won World Cup downhill races here in 2005 and 2006.
"I was definitely surprised," Vonn said.
"I made a big mistake at the top but I tried to make up time on the bottom, and I think I skied pretty well on the turns," Vonn said. "At the finish I thought it was a good time, but for sure Maria would beat me."
Vonn's win moves her to the top of the downhill standings ahead of Riesch, who leads Vonn by 52 points in the overall standings before Sunday's super combined race.
Vonn was .001 behind Kamer at the second time split, but picked up speed on the second part of the course to beat her by 0.68 seconds and the 19-year-old Gut by 0.80.
Riesch's run went from bad to worse. She was 1.09 behind Vonn on the first time split, then 1.10 and 1.95. Moments after crossing the line, Riesch looked startled, shrugged her shoulders and bowed her head.
Vonn's goals this season include breaking the American single-season record of 11 wins she set last year. She's aiming for the all-time record of 14 victories established by Swiss great Vreni Schneider in 1988-89.
Andrea Dettling was one of the first down on Saturday and crashed near the top section, flying sideways into the netting. But the Swiss skier got back up on her feet after a few seconds without assistance and appeared unharmed.
She was suspended for two World Cup races this week by the Swiss ski federation for criticizing head coach and former mentor Mauro Pini in interviews. She will miss giant slalom and slalom races Dec. 28-29 in Semmering, Austria.
Posted in: World Cup downhill 2010,World Cup downhill Champion : Lindsey Vonn