Shiffrin was second-fastest after the first run in her signature discipline, 0.11 seconds behind Sweden's Anna Swenn Larsson, but stormed to her 60th slalom victory with a spectacular second run.
With her mother and coach Eileen watching on, Shiffrin was handed the crystal globe soon after and she held it aloft while pumping her fist before kissing the trophy and acknowledging the crowd.
Shiffrin, who was out of action for several weeks after injuring her knee in January, had already won her eighth slalom globe last weekend in Are, Sweden.
"It's been a wild season so I'm really happy to be here and see the final race of the season go well. I'm looking forward to the next season already," Shiffrin said.
"It's a little bit hard to process it (the records) all. It makes me feel so invigorated and so alive, I'm trying to soak it all in.
"I never really focus too much on the numbers but now I feel OK with them. It's not pressure, it's just an honour."
Larsson looked set to pip Shiffrin to the top of the podium but made a mistake halfway through her second run, and the Swede eventually slipped to third place behind Norway's Mina Furst Holtmann.
