Kathleen, nicknamed "Kylie" from childhood, was born in Charlottetown, Prince Edward Island, the daughter of Nathan "Nat" Davenport, a Bank of Canada employee, and Doris Bridget Davenport, a former ballet dancer with the Royal Winnipeg Ballet. She lived in Charlottetown until she was 7 years old, when her father got promoted to the Bank of Canada's Ottawa head office, as a result, her family moved to the city.
Her interest in singing began at the age of 9, when she heard her brother, Ed, playing Metallica's Kill 'Em All album on his turntable. She began repeating lines from "Seek and Destroy" and "Whiplash" to her brother's amusement and her mother's dismay. Ultimately, her mother hired a tutor to get her into singing. Kylie particularly enjoyed heavy metal, citing Metallica, Anthrax, Mötley Crüe, Iron Maiden, Suicidal Tendencies, and Judas Priest as being among her favorite bands. She had become passionate about professional dance by the age of 12, despite her growing interest in heavy metal, and began attending classes at a dance school in nearby Hull, Quebec. She attended Gloucester High School in Ottawa, and graduated from Carleton University.
By the time she was 21, Kylie had been in several metal groups in the Ottawa area, notably including Seek the Fate (a grunge band, which she co-founded when she was only 16 but got kicked out of for admitting to not liking "most grunge acts not named Soundgarden") and Blinded by the Light (an industrial metal band, for which she briefly served as the female vocalist). She also sang in an all-female Def Leppard tribute band, Lady Leppard, when she was 19.
In early 1997, her mother noticed a small ad in the Ottawa Citizen announcing auditions in Toronto for a girl group, and encouraged Kylie to try out. She chose to audition, traveling to Toronto on the LRC and bringing along some of her thrash metal/grunge/nu-metal demos. The band's soon-to-be-manager Barry Berlin became curious about what it would sound like if Kylie sang pop songs. Kylie became the lead singer of the girl group, FanGirls, which she suggested the name for, claiming in a later interview that it was an in-joke about "us just trying to piggyback off the Spice Girls' success." Kylie and Leah Amanda Shiller are considered to be the lead singers of the group.
In 1998, FanGirls' European hit single "The Power" unexpectedly entered the Billboard Hot 100, despite the group not having a recording contract in the US; RCA Records (which FanGirls' label, BMG Ariola Hamburg, controlled the European operations of) had previously rejected FanGirls as "unsuitable for the American market." An exchange student from Pittsburgh returned from The Maritimes and asked his local Top 40 radio station to play the song. The track quickly became popular, and the station began distributing the song to their sister radio operations throughout the US. It shot to no. 2 on the Billboard Hot 100 after four weeks, leading to the rush-release of the group's self-titled debut U.S. album after American record stores began importing the group's first two European/Canadian albums, We're Gonna Meet Ya and Out to Party.
During the recording of FanGirls' For Sale or Lease album, Kylie formed Femme Fury with her Gloucester High School classmates Leni Larceny, Rebecca de Mercy, Roxxi Jasem, and Beth Danneberg, who were among the few girls in the school who shared her interest in heavy metal. The group made it's first album appearance on a song included on For Sale or Lease. The song, "Femme Fury", was preceded by a spoken word introduction in which Kylie critiqued the division between rock, hip-hop/R&B, alternative and pop fans, stating "As far as I'm concerned, in the end, music is just a huge family of different genres. It doesn't matter if Nick's your favorite Backstreet Boy, or if you thought Metallica ended after Cliff Burton died, at the end of the day music's just music."
On the FanGirls 500 World Tour, promoting FanGirls' For Sale or Lease album and Ladylike and Boyish EPs and Femme Fury's self-titled debut album, half of the set was dedicated to FanGirls' pop songs and the other half to Femme Fury's songs, increasing FanGirls' appeal with both middle-class teenagers and predominately male heavy metal fans.