Released as the follow-up to the duo's 1996 album ATLiens, Aquemini expands on the previous record's outer space-inspired compositions by incorporating live instrumentation. The commercial success of ATLiens allowed for more creative freedom for the group, which led to the members self-producing the majority of the tracks. The band employed a large number of musicians for the album, who frequently entered and exited the studio throughout the recording process and had a major influence on the writing development of the album's songs. Lyrically, Aquemini explores various themes including human nature, addiction, and interpersonal relationships.
The album was certified Platinum in November 1998, only two months after its release, and was certified Double Platinum on July 2, 1999 by the Recording Industry Association of America. Aquemini peaked at number two on both the Billboard 200 and the Top R&B/Hip-Hop charts. Four of the album's tracks had already or would later become singles, although some were limited (promotional) releases and not available commercially. The record also received rave reviews from music critics, who praised the album's musicality and unique lyrical themes. It was ranked at number 500 in the book version of Rolling Stone's 500 Greatest Albums of All Time.
In 1994, the American hip hop duo OutKast released their debut album, Southernplayalisticadillacmuzik, which was recorded when members Big Boi and André 3000 were 18. Bolstered by the success of "Player's Ball", the record established OutKast as prominent figures in the Southern hip hop scene. After the album was certified platinum, LaFace Records gave OutKast more creative control and advanced money for their 1996 follow-up album ATLiens. On ATLiens, André 3000 and Big Boi abandoned the "hard-partying playa characters" of their debut album in favor of personas that were more futuristic, and produced many of the songs on their own for the first time. Critics praised the group's maturing musical style on the record, which debuted at number two on the US Billboard 200 chart and sold nearly 350,000 copies in its 1st 2 weeks of release. The single "Elevators (Me & You)" reached number 12 and spent 20 weeks on the Billboard Hot 100 chart.
After the release of ATLiens, André 3000 entered a relationship with neo soul singer Erykah Badu, who was part of a burgeoning movement in the urban music scene described as "more bohemian than ghetto". André 3000 adopted a more flamboyant style of dress during performances in promotion of ATLiens that included large glasses, blond wigs, and marching band uniforms. Badu gave birth to his first child in November 1997, which presented new artistic inspiration for the rapper.
Due to OutKast's newfound commercial success and higher budget for the album, the group enjoyed a more relaxed schedule and "could really just live" at the studio. The duo and studio musicians lived and worked in the studio for weeks straight, with Big Boi noting, "It usually takes us two to three years to make a record because we take our time; we ain't giving you that fast food, trying to meet a deadline. It ain't done until it's done sonically." For Aquemini, the duo used live instrumentation and improvisation, bringing a baby grand piano into the studio and hiring musicians who played "everything from stoner funk to prog rock". Producer Neal H. Pogue recalled, "That was the beauty of making all those records – having musicians come in and out. It was almost like a Motown, that's what we had. Or like a Stax Records thing. That's what I loved about it. It brought back that whole feeling of making records. It was organic." Much of the music on Aquemini was formulated during jam sessions, in which one musician would begin with creating a chord pattern and the rest would incorporate their instruments following that sequence. While recording Aquemini, André 3000 drew influence from reggae music and listened to Bob Marley constantly during the sessions. After the musical aspects of a song were developed, André 3000 and Big Boi would then create lyrics that they felt would fit with the tone of the song.