No athlete from the continent had ever won a medal of any colour at the Winter Games, but the 25-year-old put that right with two incredible runs down the Stelvio course to hold off Swiss great Marco Odermatt by 0.58 seconds.
"I'm not even able to grasp reality," Pinheiro Braathen, who switched allegiance from Norway after briefly quitting the sport in 2023, said before the medal ceremony.
"I am just trying to get some sort of emotion here and translate it into words, though it's absolutely impossible. I just wanted to ski as the person I am."
Strains of the classic song Mas Que Nada rang out across the finish area as Pinheiro Braathen was serenaded by the Brazilians in the grandstand and wedged alongside the slope.
Down on the beaches of Rio de Janeiro, too, the caipirinhas would surely be flowing for the football-mad country's latest and most unlikely sporting hero.
"This unprecedented result shows that Brazilian sport has no limits," Brazilian President Luiz Inacio Lula da Silva posted on X.
Pinheiro Braathen has hardly emerged from nowhere.
He was the World Cup slalom champion in 2023 and is currently second in the overall standings behind Odermatt.
But no one envisaged the Brazilian opening a massive 0.95-second lead over Odermatt from bib number one in a masterful first run that left his rivals scratching their heads and only seven of them within two seconds of him.
Barring a crash or an extraordinary Odermatt surge, it looked like nothing could deny him a history-making gold in the second as the weather closed in.
Odermatt, giant slalom champion in Beijing in 2022, duly cranked up the pressure with a searing second run to take the lead, leaving last man Pinheiro Braathen 54 gates from glory.
Pushing out of the start hut in his distinctive silver helmet, he leaked away some of his advantage with a few ragged turns, but with his eyes fixed on gold the Brazilian avoided any calamities.
After crossing the line Pinheiro Braathen collapsed to the snow before getting up and holding his skis aloft to the roaring grandstand.
He then sought out his Norwegian father, Bjorn, who introduced him to the sport as a young boy, for an emotional embrace before breaking into his trademark samba celebration.
After climbing on the podium, he punched the air as the Brazilian anthem rang out for the first time ever at the Winter Olympics, and the tears of joy began to flow.
Odermatt misses out again
For Odermatt, the champion in Beijing, it means he returns home without a gold medal, having arrived in Bormio as the favourite to win multiple titles. He missed the downhill podium, coming fourth, before winning a silver in team combined and a bronze in super-G.
"I knew it would be very tough to beat him (Pinheiro Braathen) today; he deserved it," Odermatt said.
"I was here in every race, and I could show my performance. Not always 100% but always on 99% and that's an amazing achievement."
Only three years ago, Pinheiro Braathen stunned those in his sport by quitting after being crowned World Cup champion in slalom that year following a fallout with the Norwegian federation.
Opening up in a documentary, 'Lucas Pinheiro Braathen: On My Terms', he said skiing was making him miserable.
But he rediscovered the joy after returning to the colours of his mother's country of birth in 2024, and this season became Brazil's first winner of a World Cup race.
All that pales into insignificance compared with what he achieved on Saturday, however, four years after a miserable Olympic debut when he failed to finish either the giant slalom or slalom.
Pinheiro Braathen's victory also stopped the Swiss sweep after all three of the gold medals so far in the men's Alpine programme had gone to Franjo von Allmen.
The Brazilian will have another shot at gold in Monday's slalom.