Shiffrin sealed record 44th slalom victory with a time of 1:47.92, holding off Katharina Liensberger of Austria (+.19) and Wendy Holdener of Switzerland (+.43).
Slovakian snow queen Petra Vlhova, who claimed her 11th slalom World Cup win Sunday and is the overall World Cup leader, finished just off the podium in fourth.
Holdener and Vlhova were second and third, respectively, after the first run but both lost speed midway down the second run. Their errors opened the door for Shiffrin who took the win with a thrilling final run.
"There's so much energy. It's just been building up," Shiffrin said afterward. “It all just went out on that run. What can I say, that’s cool.”
Her win in Flachau is her 68th World Cup victory, leaving her just fourteen wins behind Lindsey Vonn who holds the record for most by a woman.
She also notched her 100th trip to the podium of a World Cup Tuesday and it was her first win in a slalom race – where she took gold at Sochi 2014 - since December 2019.
Those records weren't on her mind, though, she said.
"I definitely wasn't thinking about records today," said Shiffrin. "I just wanted to ski well. This slope has kind of tripped me up the last several years. I just wanted to ski strong.
"It was really fun."