Blardone made up a 0.02 second deficit on Hirscher from the first run to take victory in a time of two minutes 33.77 seconds, 0.16secs ahead of Hirscher's combined time.
It was Blardone's seventh race win of the season, level with Hirscher and American Ted Ligety, who could only manage ninth.
Hannes Reichelt finished third, with a much-improved second run lifting him up from 11th place, 0.82secs down on Blardone.
Hirscher now leads the season-long giant slalom standings from Ligety by 132 points.
In the overall World Cup standings - determining the best all-round skier from all disciplines - Hirscher leads by 92 points from Croatia's Ivica Kostelic.