The 41-year-old French actress' rep confirmed Thursday to People that Cotillard recently welcomed a daughter with the 43-year-old actor.
Cotillard and Canet are longtime friends who started dating in 2007.
The couple are already parents to 5-year-old son Marcel, and announced they were expecting again in September while dispelling rumors of an affair between Cotillard and "Allied" co-star Brad Pitt.
"Firstly, many years ago, I met the man of my life, father of our son and of the baby we are expecting. He is my love, my best friend, the only one that I need," the star said at the time.
Cotillard and Pitt played married spies in "Allied," which opened in theaters in November. The actress told Buro 24/7 in 2015 that motherhood has changed her approach to her career.
"Usually when I work I'm totally dedicated and even if I'm partly myself when I leave the set, there's something that I bring home with me. It has changed. I cannot bring any[thing] home with me because my son would freak out," she said.
"I'm totally separating my life as an actress [from a mom]. It's not that difficult," the star added.
Cotillard drew comparisons to Pitt's estranged wife, Angelina Jolie, after debuting a new look for the movie "Rock'n Roll" this month.
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