Joan Chamorro was born in Barcelona on September 24, 1962. He studied classical saxophone at the city's municipal conservatory with the teacher Adolf Ventas and took the higher degree at the Taller de Músics, the Barcelona jazz school. He plays the whole saxophone family (the baritone was his first instrument), clarinet, bass clarinet, flute and cornet, and he now plays mainly double bass. In an interview with Jazz in Europe he said he began playing at eighteen.

Through the 1990s and 2000s he was a working sideman in Catalan big bands and small groups: the Big Band del Taller de Músics, the Barcelona Hot Seven (two Taller de Músics records in 1992, one with Carme Cuesta), the Big Band de Bellaterra (Don't Git Sassy, Fresh Sound New Talent, 1998), the Eladio Reinón Supercombo (Canciones de Amor Latinas, Fresh Sound World Jazz, 1999), the Big Band Jazz Terrassa and the Fu Manchu Jazz Servants (Shanghai Shuffle, Fresh Sound, 2005). Biographies list stage and studio work with visiting Americans including Slide Hampton, Frank Foster, Frank Wess, Teddy Edwards, Randy Brecker, Gary Smulyan, Dick Oatts and Judy Niemack, and with the Cuban pianist Bebo Valdés. His first record as a leader, Baritone Rhapsody (Fresh Sound New Talent, 2011), is a baritone-saxophone tribute to Pepper Adams, Gerry Mulligan, Serge Chaloff and Harry Carney, with Scott Robinson as featured guest on tenor, baritone and bass saxophones and trumpet, and a Catalan band that includes the pianist Joan Monné and the trombonist and arranger Sergi Vergés.

In 2006 Chamorro founded the Sant Andreu Jazz Band at the Escola Municipal de Música de Sant Andreu, a program that teaches jazz to children and teenagers from about seven to twenty-one, most of whom arrive as classical students. His method rests on listening, imitation and memory: players learn tunes and solos by ear and sing them before notation is introduced, and older and younger members play side by side. By 2012 the project had outgrown the school and became independent. It receives no outside funding, students pay nothing for lessons or recordings, and concerts and record sales cover the costs. The band's first CD and DVD, Jazzing: Live at Casa Fuster, appeared in 2009, and the Jazzing series has continued ever since, with guests along the way including Ken Peplowski, Wycliffe Gordon and Joel Frahm; the series reached its sixteenth volume in March 2026. Chamorro also created the Jazzing Festival in the Sant Andreu district. He received the Premi Altaveu in 2012, and in 2021 the band won the Alícia prize of the Catalan music academy for its educational project. Ramón Tort's documentary A Film About Kids and Music portrays him and the band and won best feature at the Lights. Camera. Help. festival in Austin, Texas, in 2013. He has taught workshops far from Barcelona, from Stanford University to Medellín, Marciac and Guadalajara, and gave a master class in Ibiza ahead of the 2015 Eivissa Jazz Festival.

The band's students became the artists of his Joan Chamorro Presenta albums, in which he produces and plays bass or baritone and tenor saxophone behind a young leader. The first was Joan Chamorro Presenta Andrea Motis, made in 2010 when Andrea Motis was fifteen; Joan Chamorro Presenta Eva Fernández (2013), Magalí Datzira (2014), Rita Payés (2015), Èlia Bastida (2017), Alba Armengou (2019), Joana Casanova (2020) and others followed. Joan Chamorro Presenta La Màgia de la Veu, an album of the band's young singers, won the 2015 Enderrock Award for best album, and the Payés record won the same year's award for best new jazz project; he produced the first two albums of Rita Payés, the second being the co-billed Lua Amarela (2016). With Motis he leads the quintet billed as the Andrea Motis & Joan Chamorro Quintet, which recorded Live at Jamboree Barcelona on April 13 and 14, 2013, with Scott Hamilton as guest, and he plays in the larger projects Live at Palau de la Música (recorded June 1, 2013, with the Orquestra Simfònica del Vallès) and Motis Chamorro Big Band Live (2015). When Motis signed to Impulse!, Chamorro was co-producer, with Brian Bacchus and Jay Newland, and bassist, tenor saxophonist and flutist on Emotional Dance (2017), and he is the bassist on her Verve album Do Outro Lado do Azul (2019).

His other recent recordings carry the same teacher-and-bandleader stamp: Play Luigi Grasso's Arrangements (2017), by the Joan Chamorro Octet with Chamorro on baritone saxophone and bass clarinet, the Italian saxophonist Luigi Grasso as arranger and soloist, and Luigi's brother, the guitarist Pasquale Grasso; the 2022 album Èlia Bastida Meets Scott Hamilton & Joan Chamorro Trio, with Chamorro on bass and as co-producer; and Joan Chamorro presenta Sant Andreu Reunion Band feat. Scott Hamilton (2023), recorded in May and June 2023 at The Jazz House and the Jamboree club. The band's Christmas Songbook followed in 2025.

Chamorro is a mainstream-jazz and swing musician, and the repertoire of everything he produces is the American songbook, swing, Dixieland and bebop standards of the 1920s to 1960s, with Brazilian songs and Catalan material added over the years. He has named the music of the 1920s and 1930s (Bix Beiderbecke, Louis Armstrong, Sidney Bechet, Adrian Rollini) as a particular interest, and his first record honors the baritone line of Pepper Adams, Gerry Mulligan and Harry Carney. His best-known contribution is pedagogical rather than instrumental: a way of teaching jazz to very young children by ear and by singing, with a rotating group of American guests (Scott Hamilton, Dick Oatts, Scott Robinson, Joel Frahm) giving the students a direct link to the mainstream tradition. The results are documented by the careers of Andrea Motis, Rita Payés, Èlia Bastida, Alba Armengou and Eva Fernández, and by a discography that, counting the Jazzing and Presenta series, runs to dozens of releases on Temps Record, Jazz to Jazz and Fresh Sound.