The 25-year-old Austrian also clinched the slalom title for the third straight year and won his eighth race of the season, his third in slalom.
Kjetil Jansrud of Norway, Hirscher's only rival for the overall title, was 60 points adrift and decided not to start in Sunday's slalom.
"There was no pressure. There is only an opportunity you have when you are in my situation and it's to try to give it 100 per cent, ski as fast as you can," said Hirscher, who became the first skier to win the men's World Cup overall title for a fourth straight year. "If everything works well it's perfect and if I skied out it would have been ok as well."
Only Austrian great Annemarie Moser-Proell won more overall titles in a row — five in the early 1970s.
Hirscher finished the season with 1,448 points with Jansrud scoring 1,288 and Frenchman Alexis Pinturault third overall with 1,006.
Third after the first run, Hirscher powered down the Roc de Fer course to beat Italian Giuliano Razzoli by .83 seconds and Russian Alexander Khoroshilov by 1.09.
Hirscher trailed Felix Neureuther by 55 points in the slalom discipline before the race, but the German blew his chance after finishing 12th.
"I was definitely a tough situation, I am really sorry for Felix as he was so close to his first globe. But it is part of our sport," said Hirscher, who finished 23 points ahead of Neureuther in the slalom standings. "I am super happy, the victory made it possible and I'm thrilled."
Jansrud had to place first or second in slalom to keep his mathematical chance alive — a highly unlikely feat as he had failed to score a top-10 result in the discipline for more than nine years.
Jansrud, who won the titles in downhill and super-G this season, usually skips slaloms, the technically most demanding Alpine event.
"I didn't want any fuss about the overall, Marcel still had a shot at the slalom title and I thought it would be good to let him focus on it. It just seemed fair," the 29-year-old Jansrud said. "We all knew that gaining 60 points on Marcel in slalom would be an impossible task for me so I decided to not ski. It's all good by me."
Hirscher's fourth overall title put him level with fellow Austrian Hermann Maier, Gustav Thoeni of Italy and Pirmin Zurbriggen of Switzerland. Only Marc Girardelli, an Austrian who competed for Luxembourg, won five times.
Jansrud, meanwhile, was happy with his season after clinching the downhill and super-G titles.
"It has been a great season, I don't feel like I am losing out on the overall, I had a good fight," Jansrud said. "It has been an amazing ride this season."