Flock, who led going into the final run eight years ago but slipped to fourth to miss a medal by two hundredths of a second, made no mistake this time to win a first women's skeleton medal for her country.
Germany's Susanne Kreher took silver, three tenths adrift, ahead of compatriot Jacqueline Pfeifer. Another German, Hannah Neise, who won gold in Beijing as a 21-year-old, finished fourth.
Flock is the first Austrian woman to win a skeleton medal and the country’s second skeleton medallist after Martin Rettl took a men’s silver in 2002. She is also the oldest winner of the women's event who joined the Games in the same year.
Flock had a dream start to the night as she went out first on the third run and posted the same time as on her second on Friday – 57.26 seconds – marginally behind the track record she set on her first run and a level of consistency nobody else could match.
She then sat back and watched the three Germans who had been breathing down her neck overnight all lose ground with scruffy third runs and suddenly she had a 0.21-second cushion over Kreher, with Pfeifer and Neise looking out of the fight for gold.
Flock could be forgiven for being nervous as she contemplated her final run. In Pyeongchang she somehow found herself leading despite not managing a top-two finish in any of her three runs.
She had a scratchy run then, slipping to fourth, but now, a more mature athlete with three overall World Cup titles to her name, she was bang on the money with a 57.28 - making all four runs within six hundredths of a second of each other.
Her times were all the more impressive given her shocking starts, where she was regularly among the very worst of the 25-woman field this week but routinely made up the time with her calm, smooth negotiation of the technically challenging upper half of the new Cortina course.
"I stayed with myself the whole time. I felt incredibly comfortable from the very beginning and never doubted that I could win here," said Flock, who either side of PyeongChang 2018 finished ninth and 10th in Sochi and Beijing, respectively.
"It’s an unbelievable feeling to cross the finish line, to hear the cheering, to see the red‑white‑red flags and to be able to embrace all the team members and my family.
“I couldn’t tell what my time was (on the final run). I just knew I put down four really consistent runs and hoped that it was enough."
The skeleton programme comes to a close on Sunday with the first Olympic outing for the two-person, mixed team relay, where Germany and Britain, boasting newly crowned men's singles champion Matt Weston, will expect to battle it out for gold.