When she was 11 years old, she hired an agent to help her get acting jobs.On the decision, she stated, "I was 11 when I did a play out in Northern California and I really enjoyed it and I decided that I wanted to pursue a career, so I got an agent and did commercials and voice-overs and that sort of thing."In 2004, Mendler got her first acting role in the animated Indian film The Legend of Buddha, in which she portrayed Lucy.Mendler had the role of Kristen, a girl who attends OCD on a scholarship, and works hard to keep her good grades.She also had begun working on a film with actress and singer Lindsay Lohan titled Labor Pains, which kept being pushed back due to various conflicts and problems.In 2009, Mendler became a recurring character in the Disney Channel series Wizards of Waverly Place.Mendler portrayed the role of Juliet Van Heusen, a vampire who later forms a romance with David Henrie's character Justin Russo. Mendler would go on to appear in eleven episodes total for the series, spanning from 2009 to 2012 when the series ended.Subsequently, Mendler portrayed Candace in the NBC sitcom Undateable (2015–16) and Ashley Willerman in the musical television series Nashville (2017).
The follow-up single "Hurricane" (2013) did not achieve the same success. She moved with her family to Mill Valley, California at the age of eight.
The scene, lasting just under a minute, is later revealed to be a dream.
That same year, Mendler was the voice of the character Thorn in the video game Bone: The Great Cow Race, which was based on the Bone comic series.
In the third season, Disney Channel announced that the series would feature a same-sex couple.
This decision caused a protest from the conservative group "One Million Moms" asking Disney Channel not to air the episode.