Knight has been working as an assistant at Pixar for its recent films, including Cars, Ratatouille, and WALL-E. Knight voices animated characters as necessary, occasionally recording scratch tracks for use until a big-name actor can record their dialogue.
She had her first voice role in the 2006 film Cars as Tia, one of two identical twin Mazda Miata "sisters" who become fans of several of the race cars (The other is played by Lindsey Collins; both actors work at Pixar as assistants).
Knight continued to do voice acting in WALL-E. In WALL-E, she plays EVE (Extraterrestrial Vegetation Evaluator), a futuristic robot who descends to Earth in search of any life, specifically plants, that still exist in the 29th century. Knight claims that she had never read the script for WALL-E and made few preparations. Sound engineerBen Burtt modified her recorded voice and director Andrew Stanton decided to keep her voice with the result.