Vonn's victory in one minute and 46.56 seconds meant she broke her personal record for wins in a season and took the American to 1,908 points, 62 behind the best of 1,970 set by Croatia's Janica Kostelic in 2006.
"Victory in the season opener and another at the finals, its' important to have this consistency, to never give up," she said.
"It's a great win in the sense that the world championships will take place on the same course next year," Vonn added.
The 27-year-old, whose season started with the announcement of her divorce from husband and coach Thomas Vonn, said the support of her friends in the American team had been crucial.
"The team spirit helped me reconsider things. It rejuvenated me," she said.
Vonn, who has also won the downhill and super-combined World Cup titles, is almost certain to win the Super-G crystal globe on Thursday and is still on course for the giant slalom competition.
Despite winning almost everything her sport can offer, Vonn said she still had goals to achieve.
"To win my 50th victory in Garmisch was a highlight, as was my first home win in Beaver Creek. But I still have a lot to achieve in the next three seasons. I want to keep skiing for the fun of it but also to leave a mark in the history of the sport," she said.
France's Marion Rolland finished 0.92 seconds behind Vonn for her first World Cup podium. Rolland is best known for crashing after only three seconds in the 2010 Olympic downhill in Whistler, and images of her fall have been shown repeatedly on television and websites.
"I knew I had the potential to go for a podium I was looking for at the start of the season. The piste suited me perfectly and I managed to let the skis go for once," she said.
Slovenia's Tina Maze, Vonn's nearest rival this winter, was third. The giant slalom world champion has made the podium in every discipline this season but has yet to win a race.