Mathilde Dehaye was born in the small city of Liège (Belgium), where she took dancing classes for over a decade, trained in improvisation, and performed in various plays throughout the years. She also played some violin, sang, painted on silk and wrote poetry. 

Two months after graduating from high school, she took a leap of faith and made her way to New York City to pursue her dreams. 
She first studied Meisner at The Acting Studio under James Price, then completed a "One Year Acting for Film Conservatory" program at The New York Film Academy, and finally graduated with a "Two Year Acting Conservatory" diploma from The Lee Strasberg Theatre & Film Institute. 
From 2018 to 2019, Mathilde portrayed the pivotal character of Amity in both seasons of the J.J. Abrams & Stephen King anthology series Castle Rock for Hulu.
In 2021, she started working on another promising character named Snake for Servant, an Apple Tv+ series run by M. Night Shyamalan.
In 2022, Vertical Entertainment released the indie campy horror film The Overnight in select movie theaters in the US and in the UK as well as on VOD and digital, in which Mathilde played the leading role of Emma, shot in 2017.

She’s been called "absolutely hypnotic" by John Saavedra of Den of Geek!, "magnetic"  by Cheryl Eddy of Io9, and "fearless" by Darek Thomas of Monday Morning Critic Podcast.

Mathilde also finds much joy and inspiration in her writing.
She won The Strasberg Works Award for her first full length play Snow White and The Beast, which was tapped for production Off-Broadway in NYC, directed by Renoly Santiago (Hackers, Con Air, Daylight).
She then wrote and played the lead in her first short film, Rhythm in Me, which ended up at The Cannes Short Film Corner as well as at The Palm Springs International ShortFest, directed by Niav Conty (Small Time, Joy Ride,Outworld). Later that year, Mathilde wrote and acted in Free Your Mind, Free Yourself, a show featuring different forms of visual arts which she put together with a few other creatives.