After losing interest in acting, Kent was inspired after seeing Dancer in the Dark to pursue a career as a filmmaker. She wrote to Director Lars von Trier, asking to study under him and explaining that she found the idea of film school repellent. In 2002 von Trier allowed her to assist him as part of a directing attachment on the set of his film Dogville starring Nicole Kidman.

In 2005 Kent directed her short film Monster, which was screened at over 50 festivals around the world. In 2014 she adapted her short into a feature-length film The Babadook starring Essie Davis whom Kent had known through drama school. The film tells the story of a single mother played by Davis who must confront a sinister presence in her home while dealing with the death of her husband. The Babadook premiered at the 2014 Sundance Film Festival in the prestigious Midnight section. The film was quickly picked up for distribution in the U.S. by IFC Films. Kent did five drafts of the feature script, received most of her funding from the Australian government, then conducted a Kickstarter campaign to help raise US$30,000 to pay for set construction. The Babadook received widespread critical acclaim, with The Exorcist Director william Friedkin tweeting that he’d never seen a more terrifying film, and doubled its budget with $4.9 million in worldwide box office.

In 2006 Kent directed an episode of Two Twisted, an Australian series following in the tradition of The Twilight Zone.

In late 2014, Kent announced that, due to popular demand, a limited edition of the Mister Babadook pop-up book featured in her film The Babadook would be published in 2015. The book was written by Kent in collaboration with Illustrator Alex Juhasz, who had created the prop book used in her film. The book sold out its run of 6,200 copies.

In June 2015, it is reported that non-fiction book Alice + Freda Forever is being adapted into a film which Kent will write and direct. The book tells the real-life story of Alice Mitchell and her lover Freda Ward whom she killed in 1892. The film's Producer Sarah Schechter stated that she is "thrilled Kent shares the same passion for telling this powerful, intense and unfortunately still timely story"

Kent was recently asked if Amelia wrote the Babadook to which she replied "It was intended but never said right out. When it turns out that The Babadook is really Amelia, or that Amelia has become possessed by him, it also seems plausible that Amelia is his creator as well as his puppet. Amelia used to write children’s books, so it makes sense that she used her book-making skills to create the mysterious, haunted object that infiltrates their life. If that’s the case, the second book depicting herself as the Monster was also made by her, possibly in an insomniac trance." citation needed