The Norwegian clocked two minutes 01.32 seconds on the Planai piste to emulate Toni Sailer, Jean-Claude Killy and Bernhard Russi with a second victory in an event no skier has won three times.
"It's a huge achievement for me to clinch another gold medal today in such a difficult race. I was so tired in my mind and body crossing the finish line after fighting so hard all the way down," Svindal told reporters.
"The course was very hard and even icy in some parts and the visibility was very poor too.
"I'm really proud to have been able to produce such an effort at the given moment. I was convinced I had given my best and achieved a pretty strong run."
It was the fifth world title for Svindal, who won the downhill in Are six years ago.
The 30-year-old Olympic super-G Olympic champion has now collected gold medals in the last four editions of the world championships, clinching the combined titles in 2009 and in 2011.
The twice overall World Cup winner is also the first Alpine skiing champion to win gold in five consecutive major events including the 2010 Olympics at Vancouver where he won the super-G along with silver in the downhill and bronze in the giant slalom.
Power and strength were the keys on the treacherous and wearing Planai course as the two other men on the podium were also among the most physical athletes on the circuit.
Italy's Dominik Paris, winner of the Kitzbuehel classic two weeks ago, finished second.
"I felt pretty relaxed at the start after having done so well this winter, and I didn't take great risks at the top to save some energy for the tricky bottom section," he said.
"This silver medal is a perfect way to crown that incredible season. I'm very pleased and looking forward for a fun party tonight."
France's David Poisson was the unexpected bronze medallist, although only injuries have prevented him medalling earlier.
Poisson's performance was all the more praiseworthy as he nearly lost his pole in the final section.
"Since the start of the season, I have had fun, I managed to take risks, I have confidence in my skiing. In a one-day race, you have to take your chance and that's what I did."
Hosts Austria were again denied a medal as downhill World Cup holder Klaus Kroell had to be content with fourth place.
The demands of the course were especially evident when defending champion Erik Guay of Canada, exhausted by the succession of turns and bumps, decided to call it quits before the finish line.
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