The 29-year-old from Vancouver — who grew up skiing in Whistler, B.C. — took the gold in one minute 1.97 seconds on the course at the Dave Murray National Training Centre.
Jeffrey Frisch of Mont-Tremblant, Que., took second place in 1:02.64, while Calgary's John Kucera was third in 1:02.79.
“I kind of knew what I needed to do today to be fast,” said Osborne-Paradis. "I figured out the course right off the bat.
“It was just sticking to the plan and not taking too many risks, knowing the course was faster today.”
Osborne-Paradis returned from injury this season and battled his way back into the top-30 with several standout performances, including a fourth-place finish in the downhill in Kvitfjell, Norway, and a seventh-place finish, also in downhill, in Val-Gardena, Italy.
He finished the season ranked 13th in the world in downhill.
Frisch, who finished second overall in the Nor-Am Cup downhill standings to earn himself a World Cup spot for next season, was disappointed with the bottom section of his run Saturday.
“The top part was good. I was really happy with it,” said Frisch. “Then from the mid-section down I didn’t really execute my race plan. That’s why there’s a distance between Manny and I.
Kucera endured a challenging year on the World Cup circuit after coming back from a long-term injury he originally suffered at Lake Louise, Alta., in 2009.
“It was an okay day. There are definitely some positives to take but at the same time I need to find a way to close the gap,” said Kucera.
Chris Steinke of Gatineau, Que., was the top junior in eighth place.