AJOYO exists because a Cameroonian drummer told a Tunisian saxophonist to stop playing other people's music. Yacine Boularès, born in Tunisia in 1981 and raised in Paris, studied philosophy at the Sorbonne and jazz performance at the Paris National Conservatory before a Fulbright scholarship brought him to the New School for Jazz and Contemporary Music in New York in 2009. In the city he fell in with Jojo Kuo, Fela Kuti's former drummer, whose Afrobeat Collective Boularès joined as a full-time member after a run of jam sessions. He described what he heard in the band's rhythm section to All About Jazz: "There's a pocket to this music that is natural to Cameroonian players. When you're playing with them, it's like sitting on the nose of a jet. There is drive that can push the whole band. That's the magic. When they play, everyone locks." Kuo pushed him to write his own material. From 2013 Boularès also held a saxophone chair with the Haitian kompa band Tabou Combo, which pulled him further from the conservatory. He has called the music he made before all this "math music."

The band that came out of it started as a partnership. Boularès and the vocalist Sarah Elizabeth Charles began working together in 2009, and the group they built is unusual for putting a singer at the centre rather than out front of a horn line. The self-titled debut, released April 23, 2015 on Ropeadope, is a roll call of that idea: Charles on lead vocals, Fred Doumbe from Cameroon on bass, Alon Albagli from Israel on guitar, Foluso Mimy from Barbados on percussion, Can Olgun from Germany on piano and Fender Rhodes, Linton Smith from New Orleans on trumpet, Guilhem Flouzat and Thierry Arpino from France splitting the drum chair, and the saxophonist Jacques Schwarz-Bart co-producing with Boularès and taking a tenor solo on "Soke Ijo." Boularès wrote all eight tracks, cut at Carriage House Studio with Ian Callanan engineering and Dave Darlington mixing. In his liner notes he framed it as autobiography: "This album tells the stories of resilience I have experienced in my personal life and around me. It is the fruit of a lifelong process that has led me to transform my deepest emotions into joy."

Reviewers heard the Cameroonian material immediately. All About Jazz ran two separate reviews within four months. James Nadal, on May 2, 2015, described "a delightful hybrid of expressive vocals highlighted by regional bikutsi and makossa tempos, with a strong dose of afro-beat thrown in for good measure," and wrote that "the music exudes sophistication, yet responds to a primordial pulse," a line the band has quoted ever since. Chris M. Slawecki, on August 19, listed the members' passports one by one and landed on a comparison: Flora Purim and Airto Moreira, if they had come from Cameroon instead of Brazil. The record went out on radio from WNYC to RFI in France, Jazz FM in London and national radio in Brazil.

Five years passed before the follow-up, and the band that made it was almost entirely new. By 2019 the lineup had settled into a six-piece: Boularès and Charles, plus Jesse Fischer on keyboards, Michael Valeanu on guitar (previously with Cyrille Aimée), Kyle Miles on bass (previously with Marcus Strickland's Twi-Life), and Philippe Lemm on drums. That group released a four-track War Chant EP on October 25, 2019 as a preview, then the full nine-track album on May 22, 2020. The album came out on Shems Records, the label Boularès had founded that year, and it is a protest record: the title track goes after political lying, "Same" works through the psychology of xenophobia, "Somber Joy" addresses mental illness and addiction over Moroccan rhythms, and "Assyko" is a straight celebration with a nod to Roy Hargrove. Boularès put the argument plainly to the press: "Exposing people to our worlds and our own immigration stories develops empathy, regardless of their political views."

The album drew in a wide guest list. Vuyo Sotashe, the South African vocalist, duets with Charles on "Better Love," released as a single on April 24, 2020 and premiered by PopMatters; the trumpeter Takuya Kuroda plays "Assyko"; the vibraphonist Joel Ross takes "Syzygy"; and "Jojo's Groove," the tribute to Jojo Kuo whose advice started the band, carries a small horn section built for the occasion, with Akie Bermiss of Lake Street Dive on vocals, Darius Christian on trombone and the Israeli baritone saxophonist Eden Bareket on the low end. Jesse Fischer produced, engineered and mixed the record at Electrik Indigo Sound in Brooklyn, and Nate Wood mastered it. War Chant won Best World Music EP at the 2020 Independent Music Awards, a category that fits the four-track EP rather than the nine-track album, though the band credits the win to the project as a whole. It also submitted the record for Best World Music Album consideration at the 63rd Grammy Awards, which is a submission and not a nomination; no Grammy recognition followed.

AJOYO has kept playing without adding to the catalogue. It headlined its own release party at Joe's Pub in 2020, and since then has appeared at Bryant Park in Manhattan on August 26, 2022, on the BAMcafé Live spring bill in 2023, at Bar LunÀtico in Brooklyn on November 10, 2023, in Wave Hill's Roots and Branches series on November 12, 2023, and at Lincoln Center's Stanley H. Kaplan Penthouse for Lincoln Center Moments on October 9, 2024. A South Arts Jazz Road Tours grant of $10,050 funded a Southern run from November 1 to 7, 2019, taking the band to Alpharetta, Georgia; Kiln, Mississippi; Mobile, Alabama; Selmer, Tennessee; Washington, DC; and Baltimore. Boularès meanwhile runs a second career: the trio Abu Sadiya with cellist Vincent Segal and drummer Nasheet Waits, which works the Tunisian Stambeli repertoire; the OSOOL project of 2022, grown out of a commission to rebuild Dizzy Gillespie's "A Night in Tunisia" through Tunisian and Arabic tradition; and the Habibi Festival, the first American festival devoted to contemporary Arabic music, which he founded and curates.

The band's sound sits on a specific set of West and Central African rhythms rather than on a general idea of African music. Boularès writes over bikutsi and makossa from Cameroon, the Assiko rhythm that gives one track its title, Afrobeat learned inside Jojo Kuo's band, and the Moroccan and Tunisian material he keeps returning to elsewhere in his work. What sits on top is not a horn front line but a singer. Sarah Elizabeth Charles carries most of the melodies, and Raul da Gama described her contribution in World Music Report as "lofty vocalastics" with "an aria-like eloquence that sits majestically in the rhythmic realm of funkified Blues and Jazz." The instrumental writing keeps real solo space, and the players filling it are working jazz musicians: Joel Ross and Takuya Kuroda came in as guests off their own leader careers, and Jacques Schwarz-Bart co-produced the debut. The second album added a layer the first did not have, with Jesse Fischer's production putting drum machines and synthesizers next to the acoustic band; Jim Hynes of Glide Magazine preferred the hybrid tracks to the fully electronic ones and thought the record's politics landed because they were "free of overbearing preaching." Phil Freeman wrote in Stereogum that the lyrics are "impassioned and socially engaged, but the instrumental tracks are just as tough and high-energy." The reference points critics reach for run from Flora Purim and Airto Moreira through Earth, Wind & Fire's horn charts to Fela Kuti, whose drummer is the band's origin story.