Goggia took second place in the race on Friday but hit her left hand on the third control gate and broke two fingers.
She clocked one minute and 28.85 seconds, 0.43 seconds ahead of Ilka Stuhec from Slovenia. Germany's Kira Weidle took third place, 0.52 seconds behind Goggia.
"Yesterday it was broken, today it was already fixed," Goggia said after her third downhill victory of the season.
According to International Ski Federation (FIS) Goggia raced with a plate and nine screws inserted in her swollen left hand. She also raced with makeshift holes cut into her gloves.
"I'm really happy, I'm really grateful because it was not guaranteed at all that I could be at the start gate today," Goggia said.
"I really understand that it was a bit risky, but I said to myself that after Beijing, I could endure everything, and this is exactly what I did."
Goggia is now second in the overall standings, 50 points behind the leader, American Mikaela Shiffrin, who took fourth place on Saturday.
The last race in St.Moritz for this time will be the super-G on Sunday.