That year Stewart also played the role of Lila in the thriller, Undertow (2004).Stewart starred in the Lifetime/Showtime television film Speak (2004), based on the novel by the same name by Laurie Halse Anderson.
That same year, Stewart had a small role in the Sean Penn-directed adaptation Into the Wild.
For her portrayal of Tracy – a teenage singer who has a crush on young adventurer Christopher Mc Candless (played by Emile Hirsch) – Stewart received mixed reviews.
She featured in the dramas Camp X-Ray and Still Alice (both 2014), and the science fiction romance Equals (2015).
In 2015, she received critical acclaim for her role opposite Juliette Binoche in Olivier Assayas's French film Clouds of Sils Maria, for which she won the César Award for Best Supporting Actress.
Stewart appeared as teenager Lucy Hardwicke in In the Land of Women (2007), a romantic drama starring Meg Ryan and Adam Brody.
The film, as well as Stewart's performance, received mixed reviews.
While considered her work a "sturdy, sensitive performance", and the Chicago Tribune noted that she did "vividly well with a sketch of a role", Variety The film received Screen Actors Guild nomination for Outstanding Performance by a Cast in a Motion Picture.
After Into the Wild, Stewart had a cameo appearance in Jumper and also appeared in What Just Happened, which was released in October 2008.
She was nominated again for a Young Artist Award for her performance.
Stewart's first starring role was at age 14 in the children's action-comedy Catch That Kid (2004), opposite Max Thieriot and Corbin Bleu.
Critic Bill Goodykoontz from The Arizona Republic said that Stewart "really shines....