The 27-year-old racer from Altenmarkt in the province of Salzburg has been on the podium in downhill races six times in the last two years, but on Saturday he was center stage at last as he became the third Austrian to clinch World Championship gold in the speciality since 1999.
"I knew I had a good chance to ski well here on this difficult course but I didn't expect such a success," Walchhofer said. "My confidence helped me to ski smoothly. I was not a big favorite with the public."
After an almost perfect run down the technically demanding Corviglia course, Walchhofer beat Norway's Kjetil Aamodt by half a second and was almost a second ahead of the 1997 downhill World Champion Bruno Kernen from Switzerland.
Aamodt was surprised by the faster course and he made more mistakes than usual in the middle part of the course after clocking the fastest intermediate time.
He was able to save a spot on the podium with a strong final part which helped him to capture his 19th medal since 1991 - and his 12th at World Championships.
Kernen enchanted the crowd with his excellent performance. Last month he achieved a great comeback by winning a downhill in Wengen six years after his triumph in Italy.
Another Swiss, Didier Cuche, was fourth, ahead of the favorite, Stephan Eberharter, who did not ski as well as expected in this spectacular competition held in front of a huge crowd estimated at 38,000 people.
Canada's Erik Guay finished in sixth again, the same position he achieved in the Super-G, to finish in front of such established specialists as Ambrosi Hoffmann, Hermann Maier and Antoine Deneriaz.
Maier, who collected a silver in the super-G, was not too upset, even though he finished well out of the medals. The 1999 downhill World Champion never found his best rhythm on this course, which required great skills and strong form.
Norway's Lasse Kjus, the fastest in the combined downhill, could only manage 13th this time and combined champion Bode Miller of the United States was 16th.
American Daron Rahlves, the winner in the recent World Cup event at Kitzbuhel, clocked the 16th-best time but he was disqualified after missing the last gates.
Defending champion, Hannes Trinkl, finished up in a distant 32nd place.
Scotland's Finlay Mickel was again unlucky - as in the combined downhill. He was flagged down on his way down to the finish line after Germany's Max Rauffer crashed, missing out on a great chance for a top-10 finish.
The next competition here, the women's downhill, is scheduled for Sunday.
Italy's Isolde Kostner, the double downhill World Cup champion, is looking to win her first gold in the discipline after capturing two golds in super-G in 1996 and 1997.