Stolz crossed the line in 34.10 seconds, winning by a margin of 0.36 seconds over defending champion Laurent Dubreuil of Canada, who finished 0.02 seconds ahead of Japan's Wataru Morishige, the Olympic bronze medallist.
"I think it was a perfect race," Stolz said.
Dubreuil, who won gold in the men's team sprint on Thursday, described Stolz's performance as "otherworldly".
"He's unbelievable. It's like trying to beat Michael Jordan or something, I assume," Dubreuil said. "I feel privileged to go against a skater this good. He's doing things that we would have deemed impossible."
Dutchwoman Femke Kok was the previous youngest gold medalist, taking the team sprint title aged 19 in 2020. The youngest world champion in an individual event was Czech Martina Sablikova, who was also 19 when she claimed her first gold.
Stolz became the youngest man to win an individual World Cup race last November and dominated last month's junior world championships in Inzell, Germany.
He swept the 500m, 1,000m and 1,500m titles and earned bronze medals in the other two individual events, the 5,000m and mass start. He also won gold in the men's team sprint.
Stoles became only the third speed skater to win both junior and senior single distance world titles in the same season, joining fellow Wisconsin natives Eric Heiden and Beth Heiden.