Rebagliati, who was 0.56sec off the pace after the first leg, came back with a brilliant second run to edge out Italy's Thomas Prugger by just 0.02sec and provide a thrilling finish to snowboarding's Olympic debut.
The Canadian had a combined winning time of 2min 3.96sec. The Swiss Ueli Kestenholz took bronze, 0.12 sec behind.
"The fog and snow were so heavy at times, you could really only see a couple of gates in front of you," said the 26-year-old Rebagliati. "But I just kept trying to push myself and attack the course and hoped I would keep my board under me."Reuse content