Her victory was described as a "wonderful start" to the teenager's comeback season.
Rapley (17) finished in 1:56.97, ahead of Calgary's Terra Moran (1:57.11) and Stephanie Irwin, also of Calgary (1:57.27).
All the international competitors were aged between 16 and 19.
Rapley's father, Beau, told the Otago Daily Times it was a "fantastic result" for Taylor, who missed last year's Southern hemisphere winter due to injury.
"She's buzzing," he said.
"It's the first time she's won a FIS race and it's a really great result from her.
"It's a fairly significant win.
"She's pulled this one out of the hat."
Ski Racing New Zealand general manager Simon Mills said Rapley's win was a wonderful result for Rapley and also for New Zealand ski racing.
"There's still an awful lot to do to emulate our most successful ski racers, but it's a wonderful start," Mills said.
"It's wonderful news and for Taylor it's a significant personal best."
Mills said Rapley had earned 20 FIS points for the win, the equivalent of a 2- to 3-second improvement on her personal best time.
"We're really excited about that.
"It was a great race, a tough race and she managed to win it . . . it's a good result in terms of standing on the top of the podium."
Taylor Rapley writes a regular column in the Queenstown Times.
