Porteous (21) laced together a highly technical run that consisted of a switch right ally-oop 540, switch left double ally-oop 900, switch left 720, right double cork 1260 and a left double cork 1260.
He received an impressive score of 93.75 for this run in his first run of the finals and was untouchable for the rest of the event.
"I had a cool day.
"We’ve been training in this pipe in Aspen for a while now and today was perfect.
"The standard of skiing was so high today — the run that I landed today was arguably better than the runs I have landed in World Cups and X Games competitions," he said.
Four times X Games medallist Birk Ruud, of Norway, took the silver medal with a score of 92.50 and Hunter Hess, of the Unites States, rounded out the podium in third with a score of 90.00.
The FIS Freeski and Snowboard World Championships will be held in Aspen from March 7-16.
Porteous said he was feeling "super confident in the pipe, because of today’s result and because we have had awesome training with great weather".
With the Covid-19 pandemic wreaking havoc on the regular World Cup circuit and many athletes keen for opportunities to compete, the Aspen stop of the US Revolution tour drew a quality field.
Wanaka skier Ben Harrington finished in fifth place in the halfpipe.
