The reception was held at a private residence on 49th Street, reported the New York Post.
Attendees were required to turn off their cellphones beforehand.
The couple became engaged in 2014 and live in New York. Mary-Kate and her twin sister, Ashley, rose to fame with the '90s sitcom "Full House" and now own two fashion labels, The Row and Elizabeth and James.
Olivier, the half-brother of former French President Nicolas Sarkozy, has two kids from a previous marriage. This is Mary-Kate's first marriage.