The streaming giant is currently in development on an original film titled, "A Time Lost," with the young actress and her older sister, Paige Brown, according to The Hollywood Reporter Tuesday.
The drama, which is based on a true story by the Brown sisters, follows a long-standing feud between two Long Island families that comes to a head when one of their teenage daughter's is diagnosed with cancer.
"We are so grateful to Netflix for their confidence in us and this beautiful story, which we have spent years writing and developing," the Brown siblings said in a statement. "It's about friendship, family and overcoming obstacles when it feels like the world is pushing you down. It's been a labor of love, literally."
The project marks Mille's reteam with Netflix, who has famously starred in three seasons of the streamer's original series, "Stranger Things."
Lisa Nishimura, VP Independent Film and Documentary Features of Netflix, praised Millie and the upcoming film.
"Millie is an extraordinary creative talent," she wrote. "We've been lucky to have her in our family from the beginning of her career. It is a genuine thrill to witness Millie bring her distinct vision to the screen, now as a writer and producer, alongside her sister on this wonderful film."
Anna Klassen, an up-and-coming screenwriter, is attached to write the screenplay for "A Time Lost." Executive producers are Millie's sister, Paige Brown, and their father, Robert Brown.
There has been no word yet on casting for the film.