A third-placed finish in the final big air event of the season in Quebec City saw the 17-year-old Canadian clinch glory on home snow, Gaskell pipping Mathilde Gremuad to the title by just ten points.
Switzerland's Gremaud came first in Quebec with a score of 178.00 points but, with Germany's Kea Kuehnel second (160.50), third for Gaskell (158.00) was enough to seal glory.
"I'm speechless. I'm so happy,” said Gaskell.
Bankes and Visintin seal snowboard cross glory in Georgia
"I had a good season, even if there were little injuries along the way that meant I couldn't train as hard as I would have wanted.
“But in the end, I was able to ski well at the right time."
Gaskell's result mirrored how the men's big air title was decided, with Switzerland's Andri Ragettli finishing third (171.50) but taking the crystal globe.
Austria's Lukas Mueallauer (179.75) topped the podium, with Fabian Boesch (172.75) third but on the leaderboard, Ragettli finished 48 points clear of Norway's Ruud Birk.
Jubilant Johaug powers to 10km freestyle gold
Switzerland win first-ever mixed team ski cross World Cup event