The record-breaking Shiffrin was unbeaten in her favored discipline in the current World Cup campaign and had won 13 of the last 14 to underline her dominance.
But Vlhova, showing brilliant technique in the head-to-head parallel slalom racing, was first across the line in both legs of the final against Shiffrin, long her nemesis.
“It’s amazing, I don’t really know what to say, I finally did it,” she said.
Just 23 like rival Shiffrin, Vlhova was claiming her seventh World Cup victory, six in slalom or parallel slalom.
The other, last week in Semmering, came in giant slalom, where Shiffrin was relegated to fifth place in pursuit of her 50th World Cup victory.
Shiffrin quickly made amends with a slalom victory the next day to set new marks for wins in a calendar year, 15, and overall slalom successes, 36, to go ahead of Marlies Schild at the top of the all-time list.
Notably, Vlhova pushed Shiffrin hard on the second leg of that victory and carried that form into the knockout event held on a floodlit course at the famous ski jump venue of the Holmenkollen.
Wendy Holdener of Switzerland beat Sweden’s Anna Sven Larsson in the run off for third place and valuable World Cup points.
The first three on the podium also top the overall World Cup standings, with Shiffrin looking to retain that title.
Schwarz denies British first
The men’s event saw a first World Cup triumph for rising young Austrian Marco Schwarz, who beat Dave Ryding in the final.
Ryding was bidding to become the first British skier to win a World Cup alpine skiing event and caused a major surprise by eliminating Austrian great Marcel Hirscher in the quarterfinals.
But his hopes of overall victory were dashed as he could not match Schwarz’s speed over the two legs in the showdown for first place.
“The night event here is always special and I’m really happy with my first first victory,” said Schwarz.
Ramon Zenhaeusern of Switzerland beat veteran Swede Andre Myhrer for the final place on the podium.
The floodlit event was the first of the year as the competitors build up to the world championships in Are in Sweden next month.