She opened the World Cup season with an impressive victory and locked up a spot on the Olympic team in the process.
Thompson held off defending champion Fanny Smith of Switzerland in the women's final to lead a two-medal day for Canada at Nakiska Ski Area. Brady Leman of Calgary took the men's bronze, finishing just behind Jonas Devouassoux of France and defending champion Armin Niederer of Switzerland.
Thompson's powerful start served her well in all four heats and helped her lead from start to finish in the final.
"She had a simple plan today, it was just keep nailing that start and go," said Canadian head coach Eric Archer. "I go, 'If you can think about the start only, you're going to be skiing with the lead all day.'
"She never saw anybody's butt today and it was awesome."
Thompson, from Whistler, B.C., won a Crystal Globe last year as the overall World Cup champion and took the silver at the 2013 world championship. She said it was hard to believe that she had booked her ticket for Sochi.
"I don't know if it's really hit me yet," she said. "I don't even know. It's just super wild that I can represent Canada at the Olympics."
Thompson was the only Canadian to pre-qualify for Sochi through method-A criteria, meaning she needed just one top-12 result this season to be all but guaranteed a spot at the Games.
She fought off a nagging cold and frigid conditions on the long Mighty Peace course for the win.
"It's all about the start on this course," Thompson said. "I was in that far gate so I knew I'd really have to have a rocket-fast start and I pulled one off and just led the whole way down."
Ophelie David of France won the bronze.
In the men's final, Leman made a desperate push before coming away with a third-place result.
"It was close to getting silver there for sure, maybe a ski length or so," he said. "I just ran out of room there at the end."
Kelsey Serwa, the 2011 world champion from Kelowna, B.C., won the small final to finish fifth overall. It was a solid result in her first major race since undergoing left knee surgery earlier this year.
"I couldn't ask for more," Serwa said. "I was aggressive and making passes and stepping all over skis in front of me. I messed up the start a few times and that got me I think, but other than that I'm really happy with the outcome."
Georgia Simmerling of West Vancouver, B.C., was ninth and Calgary's Danielle Sundquist was 19th.
Mathieu Leduc of Comox, B.C., was 12th overall on the men's side. Dave Duncan of London, Ont., was 17th and Louis-Pierre Helie of Berthierville, Que., was 31st.
Montreal resident and 2011 world champion Chris Del Bosco had a poor qualification run a day earlier and didn't advance to the heats.
Two World Cups were on the original schedule this week but one event was cancelled Friday due to cold temperatures. It was a tad warmer Saturday, but it was still a frosty -24 C during the final runs.
The Canadian ski cross team is expected to officially unveil its Olympic roster in mid-January. Qualification criteria is complicated because ski cross athletes must compete with other freestyle disciplines in order to lock up spots for Sochi.
The Canadians didn't reach the podium at Nakiska last season in the event's inaugural edition. Head coach Eric Archer was quite pleased with the results this time around.
"It's awesome, it's a good start," Archer said. "Now it's race season. We're ready to go."
Canada won the Nations' Cup as the No. 1 team on the World Cup circuit in four of the last five years.