US freeskier Ferreira completes Olympic set with halfpipe gold
Ferreira, who aready had a silver and bronze in his collection, posted a winning score of 93.75 after a sublime effort on his third and final run of the competition under the lights in Livigno.
He dislodged Henry Sildaru from top spot but the Estonian's silver was still his country's first medal of the Milan-Cortina Games.
Canada's Brendan Mackay took bronze with a best score of 91.00.
"I'm finally in the history books, at least in my eyes," said Ferreira. "I would still be the same person with or without the medal, but it sure does feel good around my neck."
"They certainly didn't give it to me easy," the 31-year-old added. "I had to keep working. If they had given it to me in 2018, who knows if I would be here tonight. The universe has a weird way of working itself out."
The final, featuring 11 competitors, started in bizarre fashion with Canada's Andrew Longino the only athlete able to put down a reasonable score of 76.50 in the first run.
The pattern of mishaps continued at the start of run two but the event changed complexion when Ferreira posted 90.50 to set a new standard.
That was immediately topped by Sildaru, who scored 92.75.
But Ferreira found an extra gear on his final run and the Estonian teenager fell agonisingly short with a 93.00, forcing him to settle for second place.
Ferreira won halfpipe silver at the 2018 Pyeongchang Games and followed up with bronze in Beijing four years later.
US skier Hunter Hess, who was labelled a "loser" by President Donald Trump for saying he had mixed feelings about representing America in the current political climate, finished in 10th spot.
Speaking after the qualifiers earlier on Friday, Hess said was embracing the label and that the furore had boosted his motivation.
New Zealand's world champion Finley Melville Ives suffered a hard fall in the qualifiers that put him out of contention for the final.
It was the second serious incident in two days in the discipline after Cassie Sharpe's crash during the women's halfpipe qualifying.
New Zealand's Olympic team said Melville Ives was "stable and positive" following his tumble.
The halfpipe event carries a high level of risk as skiers must perform a series of aerial tricks by propelling themselves off the edge of a semi-cylindrical course.
The inner height of the walls is 7.2 metres and the athletes soar high above the lip of the half-pipe.