It was the first Olympic medal for Fenninger, who is fourth in this year's overall World Cup standings and who has stood on the podium three times in a super-G competition this season.
She became the third consecutive Austrian skier to win the super-G Olympic gold.
Fenninger turned in a time of 1:25.52, more than a half second in front of silver medalist Maria Hoefl-Riesch of Germany. Austrian Nicole Hosp was third. Hoefl-Riesch won the alpine combined earlier in these Olympics and Hosp picked up a silver medal in that race.
There were 49 competitors in Saturday's event and 18 could not make it safely to the bottom of the course.
Laura Gut of Switzerland, who was third in the downhill, finished fourth on Saturday. Tina Maze of Slovenia, one of the two downhill gold medal winners in what turned out to be the first alpine skiing tie in Olympic history, was fifth.
American Julia Mancuso finished eighth. Lindsey Vonn of the United States would likely have been a factor in the race had she been healthy. Vonn was the bronze medalist in the super-G four years ago, but missed these Olympics with knee problems.
One of the biggest casualties of the race was Dominique Gisin of Switzerland, who won the other gold medal awarded in the downhill but who crashed in this competition.