Police said only that the woman was discovered dead in front of an apartment building in downtown Manhattan, near the financial district and the South Street Seaport tourist area.
Korshunova had graced the covers of European editions of Elle and Vogue and walked the catwalks for designers including Betsey Johnson and Jill Stuart.
Witnesses described seeing her plunge from a ninth-floor balcony in the building on Saturday afternoon.
Local media, citing police sources, said there was no sign of a struggle inside her apartment and that Korshunova was believed to have leaped to her death.
A friend told The New York Post, however, that Korshunova had just returned from a modelling job in Paris and seemed "on top of the world."
"There were no signs," the unidentified friend was quoted as saying. "I don't see one reason why she would do that."
Korshunova, a native of Kazakhstan, had been profiled in British Vogue in recent years as a new face to watch, and she was featured in ads by Vera Wang, Marc Jacobs, Christian Dior and DKNY.
A spokesman for Korshunova's agency, IMG, which also handles Heidi Klum and Kate Moss, said "We're shocked and our heart goes out to her family," the Daily News reported.
