The 22-year-old from Bergamo came from behind to pass Lindsay Jacobellis, the American athlete who had led for much of the race, and held steady for the win.
Jacobellis finished fourth, with previous winner Eva Samkova of the Czech Republic in third and France's Julia Pereira in second.
It's the first Olympic gold for Moioli and the second for Italy, following Arianna Fontana's victory in the 500m short-track speed skating.
“Women are women: we have an extra gear. Seeing Arianna win gave me a boost and I said to myself: 'I don't want silver or bronze, I'm here for the gold,'” Moioli said.
Photo: Martin Bureau/AFP
The men's Italian team have so far brought in one silver, for Federico Pellegrino in the cross-country ski sprint, and two bronzes, for Dominik Windisch in the men's biathlon 10 km sprint and Nicola Tumelero in the 10,000m speed skating. Federica Brignone won another bronze in the women's giant slalom.
That leaves Italy ninth on the medal table overall – a marked improvement on the Sochi Games, when Italy didn't win a single gold medal and finished 22nd out of 26 countries.
Photo: Martin Bureau/AFP