Pärson performed flawlessly to clock a winning time of 1min 26.89sec in the blue riband event of the downhill to leave American Lindsey Kildow in second and Austrian Nicole Hosp in third.
Kildow came back from disaster to claim her second silver medal of the competition having been beaten to second by Pärson in the super-G, as contenders Renate Goetschl and Julia Mancuso failed to get on the podium.
Pärson thus succeeds absent Croatian star Janica Kostelic as the fastest woman on skis, and added the elusive gold in the only discipline missing from her world championships collection.
Pärson’s third win inside a week means she now has seven world titles. She claimed her first in the slalom in 2001, and in 2003 she secured the giant slalom gold.
In 2005 she won the slalom again, and also won her first speed event gold in the super-G.
At Åre, Pärson has won the super-G, the super-combined and the downhill.
And as Olympic slalom champion, she will be aiming to add more gold to her collection this week when the technical events are held.
“It’s absolutely incredibly. Words fail me. It was so unbelievably difficult and I was so close to skiing off track,” Pärson told SVT.
Austrian all rounder Hosp began with bib number 15 from the field of 30 top ranked skiers, and her solid performance on the 2.24km Olympia course knocked Swedish hopeful Nike Bent off the top step of the provisional podium.
A succession of racers followed, but only Pärson, starting with bib 27, was able to show them all how to tame it with a near-flawless run which had her in the lead from start to finish.
Thousands of flag-waving Swedes roared with approval as Pärson finished 0.48 seconds ahead of Hosp to end her hopes of a gold medal.
American contender Julia Mancuso followed but was never in the reckoning and ended her run over a second behind Paerson and out of the medals.
Kildow came closest to ruining Pärson’s chances of holding on for her third gold medal of the competition.
The 22-year-old American was only 0.14 beind her Swedish rival at the first time check, however she lost major time when she wobbled and by the midway point she was 0.86 in arrears.
Kildow did well to recover though, and finished superbly at only 0.40 adrift to claim a well-deserved silver.
Austrian ace Renate Goetschl, the 1999 downhill champion and a major favourite following her stunning six-victory season in the speed events so far, was last out the gate.
The 31-year-old was competing in her last world championships race but after falling quickly behind and finishing 1.14 adrift she failed to secure a golden handshake from the competition.