In 2005, at age 18, Kesha was signed to the label Kemosabe Records, and the music publishing company Prescription Songs. Kemosabe Records is owned by Sony Music Entertainment and located in Los Angeles. Sony Music Entertainment partnered to create Kemosabe Records. Other artists that have signed with Kemosabe Records include Juicy J, Rock City, Zara Larsson, Lil Bibby, and Becky G. Kesha later sang background vocals for Paris Hilton's single, "Nothing in This World". Kesha then signed with David Sonenberg's management company, DAS Communications Inc., in 2006. DAS was tasked with obtaining a major label record deal for Kesha in a year's time in exchange for 20 percent of her music income, with her having the option of ending the relationship if they failed. She worked with several writers and producers while at the company and ended up co-writing Australian pop group the Veronicas' single "This Love" with producer Toby Gad. While furthering her career in the studio, Kesha earned her living as a waitress. While struggling to get by, she began stylizing her name as 'Ke$ha', explaining the dollar sign as an ironic gesture.

After failing to negotiate with Lava Records and Atlantic Records in 2009, Kesha signed a multi-album deal with RCA Records. Having spent the previous 6 years working on material for her debut album, she began putting finishing touches to the album. For the album, she wrote approximately 200 songs. It was certified Platinum in the United States and had sold two million albums worldwide by September of that year. The album's lead single, "Tik Tok", broke the record in the United States for the highest sales week for a single, with 610,000 digital downloads sold in a single week, the highest ever by a female artist since digital download tracking began in 2003. It spent nine weeks at number one in the country and became the longest running number-one by a female artist on her debut single since Debby Boone and "You Light Up My Life" in 1977. As of 2019, "Tik Tok" has sold about 14 million copies worldwide, becoming the best-selling single in digital history and the best-selling digital single in history by a female solo artist. Subsequent singles from the album ("Blah Blah Blah", "Your Love Is My Drug" and "Take It Off") achieved similar commercial success, each reaching the top ten in Australia, Canada, and the United States. Kesha was also featured on two top ten singles by musician Taio Cruz and electropop duo 3OH!3.

Kesha wrote or co-wrote every song on her first two albums and considers herself a songwriter primarily, writing for artists including Britney Spears and Miley Cyrus. Along with a mezzo-soprano voice, she possesses a "strong, sneering vibrato", with a distinct yodel-like quality to her voice; she employs actual yodeling on the songs "Tik Tok" and "Cannibal". Having previously done country, pop rock, and electro, she had a clear idea of the synth-pop sound that she wanted for her debut album. The genre was popular at the time with many of her peers releasing similar sounds. Both of those albums are of the genre with catchy hooks and synthesized productions often compared to pop singer Dev by music critics, creating misunderstandings among the fans of the two. "Party at a Rich Dude's House" and "C U Next Tuesday" have 1980s derived backing, while "Stephen" begins with "Kansas-style vocal harmonies". "Dinosaur" follows a verse-chorus formula, and has a "cheerleader-type tune" reminiscent of "Hollaback Girl" (2005) by Gwen Stefani and "Girlfriend" (2007) by Avril Lavigne; the song uses the overt symbolism of dinosaurs, carnivory, and other primitive motifs to tell the story of an older man who preys on younger women. According to Kesha, the song is based on true events. While her vocals on Animal were heavily processed with auto-tune, often to produce rapid stuttering or over-pitch corrected vocal effects, leading to questions on vocal talent, she expressed confidence in her abilities, showing some of her vocal talent in the ballads "Animal" and "Hungover" on the album.