The Austrian locked up his second GS title after also winning in 2012, holding an insurmountable 185-point lead over Pinturault with only one race remaining.
"I am super happy about today's result," said Hirscher, adding he didn't ski cleanly. "Sometimes I have been far away from the perfect line."
Olympic and world champion Ted Ligety, who has dominated the discipline since a rule change for GS skis three years ago, finished the race in fourth and the American was bumped to third in the standings.
"I was the last one to win with the old skis in 2012," Hirscher said. "For me it was a long way to get back on the first position in GS racing. It took us a lot of energy. About 80 per cent of my training went into GS."
Hirscher became the second skier after Kjetil Jansrud to lock up a discipline title before the season-ending World Cup finals. The Norwegian secured the super-G crystal globe last week.
In the hunt for overall title, Jansrud lost further ground on Hirscher, who is now 124 points in front. The Norwegian came almost four seconds off the lead in 23rd and earned just eight points.
"It's really cool, but it's too early to start celebrating," said Hirscher, who was expected to soar further ahead after Sunday's slalom, which Jansrud is skipping.
Jansrud had already left the finish area after his second run when his rival Hirscher raced just minutes later.
"We all know that Kjetil is a really great skier," Hirscher said. "If he is in a good shape he can win two races in Meribel, easily. There is still a long way ahead of me."
Pinturault extended his first-run lead to finish in a total time of 2 minutes, 19.78 seconds, 0.68 ahead of Hirscher. It was the Frenchman's ninth career win but first in GS since February 2013.
Pinturault's compatriot Thomas Fanara came 0.94 back in third for his seventh career podium, though he is still awaiting his first win.
"It was just amazing because I made this mistake," Pinturault said, referring to a tough start to his opening run when he struggled between the first couple of gates.
"For me, after the first run, the main goal was to push harder in the second run," he said.
Ligety had to win the race to keep his mathematical chance of retaining his GS title but was already 1.49 off the lead after the opening run.
"I hit a pebble on like the seventh gate and I had no grip on my left foot the whole way down, just hoping to stay in. Survival mode," Ligety said. "Luckily I am not too far out."
Ligety, who won here six times and had been on the podium every year since 2007, finally improved to fourth, trailing Pinturault by 1.88.
"The hill has always been good for me. I really like the flow of this hill," the American said, adding he had "some good turns but some big mistakes as well" in the second run.
Henrik Kristoffersen was the fastest skier in the final run and improved to sixth from 23rd after the opening run. The 20-year-old Norwegian, who earned his first career GS podium here last year, successfully defended his junior world titles in slalom and GS this week.
Sunday's slalom on the same course is the final World Cup race before the finals in France.