Mathilde Seigner (born January 17, 1968) is a French actress.

Mathilde Seigner was born in Paris, France. She is the granddaughter of the respected French actor Louis Seigner (1903-1991). She is the sister of the actresses Emmanuelle Seigner (and sister-in-law of Roman Polanski) and Marie-Amelie Seigner, and the niece of Françoise Seigner. Since 2006 she has been the partner of Mathieu Petit, a cameraman, and their first child, a son Louis, was born 10 August 2007.