Innerhofer, with a time of 1 minute, 37.83 seconds, nipped Georg Streitberger of Austria by 0.12 seconds on the same mountain where he won three medals at the 2011 World Championships.
The course had to be shortened due to heavy snow this week, which made preparations for the early stages of the track difficult.
"I knew the steep part is where I can do my best and I knew that's where I needed to make up the time I might have lost at the top," said Innerhofer. "On the last jump I felt confident that I had a good run but I really had no idea it would be fast enough for a victory."
Two of Streitberger's Austrian teammates -- Klaus Kroell and Hannes Reichelt -- placed third and fourth, respectively. Aksel Lund-Svindal of Norway was fifth and American Marco Sullivan was 19th.