After booking a small part in an independent short film in 2009, she won her breakthrough role in the 2011 feature The Year Dolly Parton Was My Mom, for which she received a Young Artist Award.

In an interview with the National Post, Stone's mother stated, "It felt like it was important for Julia to spend another year becoming her before throwing herself into becoming other people.

"[9] She appears in the opening scene of the 2012 series Emily Owens, M.D., playing a girl named Abbey who initially ridicules the main character, but later comes to admire her.

[10][11] Following other guest parts, and additional work in shorts, Stone booked her first role as a series regular in the TV show The Killing, which she appeared on in 2013.

"[12] While reviewing her work in the role, Pamela Thomas of The Reel Spin noted, "Not only is Stone fearless, gorgeous, and wise beyond her years, she does it all with an effortless grace.

Courtney Small of Cinema Axis noted, "The confines of a swimming pool serve as the perfect metaphor for the awkwardness of adolescence," and called Stone's performance "outstanding.

"[2] For her work in the role, Stone was chosen as a Toronto International Film Festival Rising Star, received recognition from E!, and won the Leo Award in the category of Best Lead Performance.

The Vancouver Sun noted, "It becomes clear watching Weirdos that the story is being told from Alice's point of view, something Stone said she didn't realize was happening during filming.

[9] Her co-star Taylor Hickson, who plays her twin, was complimentary while noting their rapport, calling Stone "amazing and a sister to me in every way.

"[26] In November 2016, The Hollywood Reporter announced that Carlos and Jason Sanchez had cast Stone in Allure, opposite Evan Rachel Wood.

[27] Unlike Stone's earlier work in The Killing, the narrative explores mental trauma, manipulation of a minor, and explicit sexual themes.

[28][29] An early review from the Toronto International Film Festival called the tale "a psychological thriller that focuses on a disturbing and obsessive relationship.

[33] In June 2018, Stone finished work on the dramatic film Honey Bee, in which she plays a sex-trafficking victim who enters foster care.

[34] Mark Hanson of In The Seats gave the film a mixed review, noting, "Stone commits to an all-consuming role that requires her to be in every scene but it's too bad that most of her big moments end up feeling calculated like awards-show clips.

[3][2] Wet Bum director Lindsay MacKay noted, "Our movie is about the unsaid little moments, and with Julia, you can be on her face for 30 seconds and go through five emotions".

[3] While reviewing Stone's performance in Allure for The Mary Sue, Teresa Jusino recalled, "You saw every emotion on her face and in her body, and so much of what she conveyed was outside of her dialogue.

[40] While reviewing her style, Matt Fagerholm of RogerEbert.com declared, "If you're searching for the emotional truth in a scene, you won't have to look any further than Stone's face.

[6] To immerse herself in roles, she began listening to songs she felt fit the tones of particular scenes, and wrote background stories about her characters.