The 24-year-old Austrian finished behind Lara Gut at the World Cup Finals but built an unassailable 215-point lead over her Swiss friend with two races remaining this weekend.
"It's just, 'Wow,'" said Fenninger, the first Austrian woman to win the overall title since Nicole Hosp in 2007. "It means that you are the best skier in the world over the whole season."
Fenninger's path to Alpine skiing's most prestigious honour was made easier when her closest challenger, Maria Hoefl-Riesch of Germany, sustained season-ending injuries after crashing in the downhill on Wednesday.
Still, her consistency over a tiring five-month season earned her the honour of becoming the 27th different women's champion since the World Cup launched in 1967.
"You can't win the overall because you are lucky," Gut said. "You win the overall because you are the best."
Fenninger carried the momentum of her Olympic exploits, including silver in giant slalom, into a surge of points in recent weeks. Her only slip since Sochi was a sixth-place finish in the final downhill on Wednesday, racing minutes before Hoefl-Riesch crashed.
"I was so nervous yesterday it was not normal," Fenninger said. "But I learned from yesterday for today and I'm stoked that I can show my good skiing again."
Tina Weirather of Liechtenstein, who was second in the overall standings heading to Sochi, also was lost for the season when she crashed in training on the Olympic downhill course.
Starting just before Gut on Thursday, Fenninger punched the air with her right fist after crossing the line, then blew a kiss to the television camera while waiting for her rival in the finish area.
Gut then finished in 1 minute, 17.14 seconds on the sunbathed course, 0.61 seconds faster than Fenninger. Tina Maze of Slovenia, the defending overall champion, trailed Gut by 0.95 in third.
Marie-Michele Gagnon of Lac-Etchemin, Que., did not finish.
Gut's victory, her second straight after her downhill success, clinched the season-long super-G title, a first career World Cup trophy for the 22-year-old Swiss racer.
Gut looked up at the giant screens, pumped both fists and basked in a loud ovation from a 5,000-strong home crowd.
"It's cool," the 22-year-old Gut said. "Winning it at home and finally bringing a (crystal) globe back to Switzerland, it's amazing."
Gut's seventh World Cup race win this season is the most on the women's circuit, and leaves her third overall.
Fenninger, however, won three giant slaloms — including back-to-back races last week in Are, Sweden — and racked up podium finishes.
She finished second in the downhill standings, behind Hoefl-Riesch, and in super-G. She also stands second in the giant slalom race behind Jessica Lindell-Vikarby of Sweden. The final GS race closes the season on Sunday.
By then, Austria hopes Marcel Hirscher will have clinched the men's overall title to give the Alpine nation its first double success since 2002.