The 32-year-old headed into the closing event in Italy the 50km classic mass start having climbed the podium in both of the cross country skiing events he had entered.
However neither of those trips were to collect gold as Olsson had to settle for silver behind Peter Northug in the 15km freestyle and Norway again in the men's relay.
But it was a case of third time lucky for Olsson as the curtain came down on the Nordic World Ski Championships with the Swedish skier producing one of the greatest performances ever.
Olsson broke away just after the 10km mark being joined in doing so by Dario Cologna however he was to escape the Swiss skier with 30km left to go after a fall saw him gobbled by the pack.
Between the 20.5km and 22.9km marks Olsson had built a lead of 26 seconds, which he somehow maintained all by himself to win by just shy of 13 ahead of Cologna.
Olympic 50km classic bronze medallist Olsson effectively went a remarkable 30km all by himself with the rest of the field unable to reel him in as he clocked a winning time of 2:10:41.4hours.
There were expectations that Cologna would catch him up but he couldn't as he finished 12.9seconds behind for silver while Alexey Poltoranin claimed bronze another 3.9 further adrift.
That marked Olsson's first World Championship title and also Sweden's first in the 50km classic mass start since Torgny Mogren's victory in Falun 20 years ago in 1993.