Born in Barcelona in 1967, he studied piano, scales and symphony at the Conservatori Municipal de Música in Barcelona and at Taller de Músics and attended master classes by piano players Bruce Barth ad Hal Garper. He received higher degrees from INCANOP (1994) and Escola Superior de Música de Catalunya (2009).
He has collaborated with many groups and has recorded with musicians such as Randy Brecker, Michael Mossman, John Mosca, Robin Eubanks, Dennis Rowland, Theo Bleckmann, Chris Kase, Alan Skidmore, Jorge Rossy, Peer Wyboris, Jordi Bonell, Juan Munguía, Adam Kolker, Bob Sands, Perico Sambeat, Chris Higgins, Omer Avital, Gary Willis, Jeff Fiuczinsky, Kirk Covington, Armand Sabal-lecco, Horacio 'El Negro', Gonzalo Rubalcaba, Dick Oatts, Niño Josele...
Besides his jazz projects (some of them promoted with his own trio) Joan Díaz is the composer of soundtracks for many short and long films (to be highlighted his tight collaboration with filmmaker Cesc Gay, composing the soundtracks for Hotel Room, Krámpack, En la ciudad *or *VOS, among others... and he has envisioned and created shows merging diverse disciplines such as the montages El centre del món and Dalirògena --both incorporating audiovisuals-, Electra -welcoming the participation of contemporary dance- or the most recent Gemini XI around the figure of Joan Josep Tharrats (2018), co-founder of Dau al Set.
Awarded five times by the Associació de Músics de Jazz and Música Moderna as the best piano and keyboard player of the year, Joan Díaz surprised both public and critics with his work* We Sing Bill Evans, for which he received the Critic's prize award of the magazine JAÇ (2008) and was a finalist for the ARC awards (2009). November 20th,2010, in the context of the 42nd Voll-Damm Internacional Jazz Festival of Barcelona, Díaz presented *Benestar/Peaceful, his first work as a piano soloist vith the special collaboration of saxophonist Perico Sambeat. This álbum, released by Nómada 57 and recorded during his premiering concert at Canal Mezzo is, according to the critic I. Ortega (Distritojazz) "[...] an intimate and collected album full of feelings and musical exquisiteness".
In 2011., Discmedi re-edited his first album MostrebÚ *(Díaz, Mengual, Gómez), and launched again the highly acclaimed work *Dalirògena (Díaz, Robles, Pérez, Mengual, Xirgu), in addition to editing their project as a quintet We Sing Wayne Shorter. With this work, Díaz became finalist to the award Premis Enderrock 2012 (Best Jazz Album), and finalist to the IV edition of the awards Premis de la Música Independent.
At the same time, Joan Díaz is a recognized musical arranger thanks to the award received for his work in Univers Evans: David Mengual Free Spirits Big Band, being the main arranger. Because of his collaboration with Niño Josele, Díaz performed several trio concerts with Josele and contrabass Pau Lligadas, among them the opening of the cycle of chamber at the Festival Mas i Mas, at Palau de la Música Catalana, august 2013.
In 2013 Díaz launched* Live al Teatre Kursaal Theater *next to Niño Josele and Cobla Sant Jordi - Ciutat de Barcelona (Discmedi/Warner, 2013). As Arion Molina notices about this work: "[...] The emotion of songs such as Minha makes me believe that this beautiful work will become a referent in the world of fusion".
In 2014 he creates The New Catalan Ensemble (NewCat), a project that revolves around the fusion of jazz and traditional root music, and the first album counted with the participation of Andrea Motis and saxo player Joan Chamorro as visiting guests. Díaz launched the first álbum of NewCat on february 2014, at Auditori de Barcelona after being featured Mercat de Música Viva de Vic and Festival Temporada Alta.
From that moment on, Díaz has published Cadena tròfica (2015) with David Mengual and Oriol Roca, featured at Mercat de Música Viva de Vic (2016), and he has composed Rèquiem a Enrique Morente, a production by Taller de Músics premiered December 2017 in within the frame of the 49th Voll-Damm Festival Internacional de Jazz of Barcelona, with the direction of Joan Albert Amargós and fifty more musicians on stage, among them the voices of Arcángel, Kiki Morente, Pere Martínez and Paula Domínguez. In 2018, Joan Díaz presented the educational project Bestiari after texts of Josep Carner with 22 original songs performed by artists such as Gemma Abrié, Roger Mas, Gemma Humet, Marc Parrot, Joana Gomila or Carles Belda, among others (again, under the umbrella of NewCat).
Besides producing the albums that he has led, Joan Díaz has also acted as a music producer in works such as Skyline *of Xavi Torres, *Ruralisme il-lustrat or Out of trad, both of Manu Sabaté or (d)ones de Les Anxovetes, among others.
As a docent, he has taught History of Music at the Centre d'Estudis Montseny (1989-90), the Blue Train in Sabadell (1990-1991 al 1996-97) and Alois Haba (1997-98); Improvisation and instrumental groups at Aula 7; de Piano and Harmony at the first Seminary of Jazz of Saragossa, at the Masterclass in Menorca (Maó); piano and combos at Seminari Internacional of Zarautz (editions I/III/IV/V), at the first Seminary of Jazz organized by the Conservatori of Albacete, a the Seminary organized by the Escola Municipal de Música of Saragossa, at the Seminary of Música Moderna i Improvisació in Monforte de Lemos and at the Seminari Internacional de Jazz i Flamenc (2008) sponsored by Taller de Músics (Barcelona). Between the years of 2002-2003 and also 2005-2006 he was the piano and combos teacher at Musikene (Centre Superior d'Estudis Musicals del País Basc). He has also been the deputy director of the Higher Degree of Music at Taller de Músics during the academical year 2009-2010.
He is currently teaching piano, improvisation and composition at Escola Superior de Música de Catalunya (ESMuC) and collaborates with Taller de Músics.
Díaz is a member of the group of composers of ESMuC Jazz Project, together with Lluís Vidal, Joan Monné, Francesc Capella and Joan Sanmartí.