Starting third on the grid, Piastri survived an opening lap crash after he was sandwiched between two cars.
One of his opponents — pole-sitter Sebastian Fernandez — ended up retiring from the race.
Piastri was able to overtake Lirim Zendeli on turn three to grab the lead, which he held all the way until the chequered flag.
Speaking to Wide World of Sports following his first F3 race, Piastri said he was surprised he pulled through unscathed.
“Yeah, turn one was very eventful,� Piastri said.
“I was pretty surprised that my front wing and my front left wheel didn't depart. As soon as I felt the hit I thought ‘there's no way I'll be making it past the next corner'.
“It felt like a big hit, but I was pretty lucky because Fernandez hit my tyre instead of the front wing.
“I think the front wing copped a bigger hit when I got shoved into Zendeli on the right hand side. I was thinking it was all over after 10 seconds.
“But it turns out Dallara build a pretty strong car.�
The Renault young driver academy member said he had received two special messages after his breakout win.
F1 star Ricciardo and four-time F1 world champion Alain Prost sent their congratulations to the up-and-coming star.
“I had an Instagram message from Daniel to say well done, which was cool, and also Alain Prost,� Piastri said.
“I got a ridiculous amount of messages, but obviously when a world champion and also Australia's current F1 driver get in touch it really sticks with you.�
Piastri will look to continue his success this weekend in the second round.
You can cheer on the Aussie teen on Fox Sports or Kayo.
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