After moving to Los Angeles, she was hired for a job at Quixote Studios as a receptionist. In 2005, Laguna Beach star Lauren Conrad and her best friend and roommate Heidi Montag moved into her building to shoot their MTV show The Hills. Patridge was cast in the series as a friend of Conrad and Montag. In the second through fifth seasons of The Hills, she had been working for Epic Records.
On May 28, 2009, she confirmed during an interview on On Air with Ryan Seacrest that she was leaving The Hills to star in her own reality program documenting her life outside The Hills. Her final episode of the series was supposed to be on December 1, 2009. However, she later signed on for the series' sixth (and final) season while her new series, produced by Mark Burnett, set to air on MTV in mid 2010, was put on hold due to The Hills. Patridge appeared in more episodes of The Hills than any other cast member.