Perry was born in Santa Barbara, Santa Barbara County, California, United States. The middle child of two pastors, she grew up listening to gospel music and singing in church. She graduated from Dos Pueblos High School in Goleta, California in 2003 and immediately moved to Los Angeles at the age of 18.After Steve Thomas and Jennifer Knapp signed Perry to their label Red Hill Records, she released her first CD Katy Hudson in 2001, a Christian gospel album.In her teenage years, Perry found a Queen album with her friend, and later said, "From then on, they have been my biggest influence". Also among her musical influences are Alanis Morissette, Heart, and Joni Mitchell, as well as the Incubus album Morning View.She changed her surname to Perry because "Katy Hudson" was too close to Kate Hudson. Perry is her mother's maiden name. Perry's biggest influences are pop rockers Cher, Cyndi Lauper, Pat Benatar, Joan Jett, and Shirley Manson, who, Perry says, "came out with a vengeance".

In 2004, Perry worked for the record production team The Matrix, who had previously worked with Avril Lavigne, Liz Phair, Hilary Duff, Skye Sweetnam, Korn and Britney Spears, among others. Perry also began working on a debut mainstream album, writing with Glen Ballard, which was due for release in 2005; some of the collaborations included "Box", "Diamonds" and "Long Shot," which were released on Perry's official MySpace page. Her burgeoning music career led to her being named "The Next Big Thing" in October 2004 in Blender Magazine, where Perry stated she wasn't "a typical Christian", mentioning that she had done "lots of bad things" during her adolescence. One of the tracks she recorded with Ballard, "Simple", was released on the soundtrack of the 2005 film The Sisterhood of the Traveling Pants. In 2006, Perry appeared on P.O.D.'s single, "Goodbye for Now". She has openly talked about her struggles within the music industry, such as being dropped from record labels for much of her early career. Her songs eventually captured the attention of Virgin Records CEO Jason Flom, who was the head of Capitol Music Group, and she signed to Capitol Music in early-2007. Perry is now regularly heard on MTV, VH1, as well as commercials. She most recently appeared on the MTV VMA Awards singing Madonna's hit single, "Like a Virgin".