The 18-year-old considers herself more of a technical specialist and was only competing in the downhill for the second time in her career. She finished in one minute 7.73 seconds, beating out Olympians Marie-Pier Prefontaine and Erin Mielzynski.
"It's definitely unexpected," said Remme, who was also the top junior. "I've always been more invested in the technical events and I just did my first downhill a couple of weeks ago. The goal is always to become the best all-round skier but I've never really thought about downhill."
Remme was third-fastest in Thursday's training run.
"I knew I was skiing the top really well," Remme said. "A little lower down I ran into some soft snow and I was really (mad). I got fired up and I think that helped me in the next part."
Remme was third in slalom at the Audi Coupe Nor-Am Cup finals last week and finished the season ranked fourth in the overall slalom standings. She's seen as one of the top up-and-coming skiers on the women's team but even her coach said she caught a lot of people by surprise Friday.
"Even this year she was a little bit reluctant to do downhill," said development team coach Peter Rybarik. "We believe it will help her in the future but it was Roni who decided that at world juniors she would do her first downhill.
"Her result (Friday) was surprising for some people but we knew she had the ability. It's good to see because although she's focusing more on slalom this shows she's not afraid to ski fast."
Prefontaine, from Saint-Sauveur, Que., was second in 1:07.89 while Collingwood native Mielzynski was third in 1:08.09. Neither racer is considered a downhill specialist.
"It's my first downhill race in three years but I loved it," said Mielzynski.
Larisa Yurkiw of Owen Sound, Ont., won the downhill in 2013 but she wasn't able to defend her title due to injury.