American star Shiffrin off to rapid ski season start in Soelden
The American, wearing the number one bib, timed one minute and 05.82 seconds, to finish 0.22 seconds ahead of Alice Robinson of New Zealand.
Italy's Federica Brignone, who has silver and bronze Olympic medals in the event, was third, 0.40 seconds behind Shiffrin.
The second run is scheduled for 12:00 BST.
Lara Gut-Behrami, last year's overall World Cup champion, pulled out before the start saying she did not feel "ready" to ski.
"I am sad, but it's the right decision," she told Eurosport.
Shiffrin had to sit out the end of the 2023-2024 season after damaging ligaments in a crash in January on the Cortina d'Ampezzo downhill course.
She said this week she would not race any World Cup downhills this season, focusing on more technical events as she aims to become the first racer to win 100 victories on the circuit - she currently has 97.
