The 30-year-old began dating the businessman in 2012, and in November 2015, the pair became husband and wife in a private ceremony in New York City.
Mary-Kate, who, along with her twin sister Ashley, is known for keeping her private life private, refused to comment about the wedding reports at the time.
However now, during an interview with Net-A-Porter’s The Edit magazine, the star has finally confirmed her marital status and opened up about life as a wife and step-mother to Olivier’s two children from his previous marriage to Charlotte Bernard.
“I have a husband, two step-kids and a life; I have to go home and cook dinner,” she shared to The Edit about her normal daily routine.
And while Mary-Kate leads a busy life, running a successful fashion business empire with sister Ashley, she still manages to find ways to relax.
“I ride horses on the weekends,” she continued. “You find the thing that helps you relax and if you don't have it, you have to look for it. Or you get burned out and then you're not productive.”
The sisters have managed to remain primarily out of the spotlight since their acting days, and Ashley has put it down to their decision to stay away from social media – instead, focusing on their fashion lines The Row and Elizabeth and James.
“Because we don't dive into that whole world [of social media] and we don't have Facebook, we've never been connected to our fans in that way,” Ashley said in the joint interview. “We've stayed quite sheltered in that sense.”