The movie, starring Tony Leung and newcomer Tang Wei, will screen during the Toronto International Film Festival before opening in New York Sept. 28 and expanding to more U.S. markets Oct. 5.
Focus Features, the film's distributor, was said to have accepted the MPAA rating without a fuss, Variety reported Thursday.
"As with so many of his previous films, Oscar-winning director Ang Lee has crafted a masterpiece about and for grown-ups," said Focus Chief Executive Officer James Schamus, who co-wrote "Lust, Caution" with Wang Hui Ling.
The Mandarin-language, sexually explicit film is based on Eileen Chang's short story about a shy Chinese drama student drawn into an assassination plot against a Japanese collaborator during World War II.
The MPAA created the NC-17 rating in 1990 as an attempt to remove the stigma of an X rating.
Lee's last film, the provocative "Brokeback Mountain," earned him the Academy Award in the director's category.