The World Cup holder in the discipline produced two near-perfect runs on the demanding Podkoren piste for a total time of 2 min 13.42 sec and his second triumph of the season.
His usual smooth and elegant skiing style left Austria's Siegfried Voglreiter a distant second in 2:15.06 with the Norwegian, Kjetil-Andre Aamodt, third in 2:15.78.
"I am amazed at how strong I was today. I was definitely not expecting to win by such a big margin," Von Gruenigen said. "It is a very difficult and bumpy hill, but such conditions have always favoured me.
"One of my goals has always been to win on all the classic giant slalom slopes. Now I have completed this list with my victory here and at Alta Badia [in December]."
"If you look at the golden book of ski racing then you can see that all the big names, such as [Ingemar] Stenmark, have won here in Kranjska Gora," he said. "I am very proud to have my name on this list."Reuse content