The Dark Knight Rises star and her partner, actor/director Guillaume Canet, became parents to son Marcel in May last year (11), and the Oscar winner admits her little boy has brought her more joy than she has ever known.
She tells Britain's Harper's Bazaar magazine, "Since having Marcel, every day of my life has been alight with him.
"One of the things I have learned recently is that I have the ability to be happy. I have found that in my family. And that is a new thing. And that hasn’t always been the case for me - so I know how lucky I am."
Cotillard began dating Canet in 2007, although they first worked together in the 2003 romantic comedy Love Me If You Dare.