Italian Luca Matteotti won the men's race, beating out Canadian Kevin Hill. American Nick Baumgartner took bronze. Another American, Nate Holland, crashed and placed fourth.
Hill, who is from Vernon, B.C., was fifth at the Sochi Olympics.
Nelly MoenneLoccoz of France was the fastest starter and led the women's final before being overtaken by Jacobellis, who also won the word title in 2005, '07 and '11.
Moenne Loccoz took silver and Michela Moioli of Italy won the bronze medal.
Canada's Dominique Maltais didn't qualify for the big final, but she won the small final.