Shiffrin looked in total control as she flew down the course in Austria during her first run for a staggering time of 1:07.89, at the time 1.24 ahead of the next best competitor, last year's winner Tessa Worley.
The American, who dominated the circuit last season, looked as relaxed as possible after an off-season where she's stressed the importance of keeping her feet on the ground and focusing week to week.
'This is a masterclass!' - Shiffrin produces storming first run of the season
The majority of the opening riders struggled to keep pace with Shiffrin, that was until 17-year-old Alice Robinson took to the slopes.
The New Zealander showed that she wasn't afraid to take risks, a key factor on this course according to Eurosport expert Finlay Mickel, and she was rewarded with a time of 1:08.03, just 0.14 behind Shiffrin.
17-year-old Alice Robinson goes toe to toe with Shiffrin in first run
The Junior World Champion is one of the most exciting young athletes across all of skiing and she lived up to the billing with a fantastic leg.
Great Britain's Alex Tilley skied hard for a time of 1:10.86 and she now faces an anxious wait to see if she qualifies for the second run.
You can watch the second leg live on Eurosport 2 at 11:50.
Soelden First Leg Top 10
1. Mikaela Shiffrin (America) 1:07.89
2. Alice Robinson (New Zealand) 1:08.03 (+0.14)
3. Federica Brignone (Italy) 1:08.75 (+0.86)
4. Meta Hrovat (Slovenia) 1:08.84 (+0.95)
5. Mina Fuerst Holtmann (Norway) 1:08.95 (+1.06)
6. Tessa Worley (France) 1:09.13 (+1.24)
7. Petra Vlhova (Slovakia) 1:09.36 (+1.47)
8. Thea Louise Stjernesund 1:09.55 (+1.66)
9. Francesca Marsaglia (Italy) 1:09.73 (+1.84)
10. Viktoria Rebensburg (Germany) 1:09.76 (+1.87)