Gianni Iorio was born in Foggia, in Puglia, on March 9, 1972, and came to the bandoneon by way of the piano. He graduated in piano from the Conservatorio "Umberto Giordano" in Foggia (in 1994, per Italian Wikipedia) with honors and special mention, and his Discogs biography lists further study with Franco Scala, Sergio Perticaroli, Massimo Bertucci, Jörg Demus and Carlo Bruno. His own biography credits him with first prizes in national piano competitions, including the A.M.A. Calabria competition in Lamezia Terme in 1983 and 1991. After studying the accordion he turned to the bandoneon, the button-keyed concertina of Argentine tango, and dates his career as a bandoneonist from 2001.

The partnership that defines his catalog began earlier. In 1996 he started playing as a duo with the Foggia-area pianist Pasquale Stafano, working through jazz standards, film themes and arrangements of Astor Piazzolla. In 1999 the two founded the Nuevo Tango Ensamble, which released Astor's Mood (Realsound, 2002) as a quintet, by the duo's own account, and then continued as a trio. The group's later records are A Night In Vienna - For Astor Piazzolla (Philology, 2005), a live set of Piazzolla repertoire, Tango Mediterraneo (Jazzhaus Records, 2008) and D'Impulso (Jazzhaus Records, 2011). On Tango Mediterraneo the clarinetist Gabriele Mirabassi joins on five tracks (1, 4, 6, 8 and 9), and Discogs credits Iorio on bandoneon and accordion alongside Stafano and the bassist Alessandro Terlizzi. His biography names "Giorni di Marzo," a piece on D'Impulso, among his own compositions.

In 2016 the duo returned to its original two-person format on Nocturno, released in May by Enja Records, the German label founded by Matthias Winckelmann, who is credited as executive producer. The program mixes Piazzolla ("Verano Porteño," "Invierno Porteño," "Adios Nonino") with pieces by other tango composers and the duo's own "Le lanterne di Phuket" and "Sagra d'estate"; All About Jazz reviewed it. Mediterranean Tales followed on Enja, recorded at Artesuono Studio in Cavalicco, near Udine, in June 2018. It is a set of six original pieces (four by Stafano, and "Nature" and "Chacarera Gringa" by Iorio), which the duo has described as a departure from its tango-centered work toward music inspired by Mediterranean voyages.

Beyond the duo he has worked in jazz settings. In September 2018 he recorded Tango Nuevo Revisited for ACT with the Javier Girotto Trio, a baritone saxophone, bandoneon and piano reading of Piazzolla and two Gerry Mulligan pieces, with Alessandro Gwis on piano and electronics. The same year he played on Tramas (Alfa Music, 2019) by the pianist Francesco Venerucci, which features Dave Liebman as special guest. A run of Puglia-based sessions puts him on records by the singers Silvia Anglani, Serena Spedicato and Mara De Mutiis, the pianist Marco Contardi and the duo Nunzio Ferro and Casinò Babis, and he is credited on bandoneon on Fiorella Mannoia's pop album Sud (2012). His biography also lists roughly ten years with the film composer Luis Bacalov, including a place as soloist in Bacalov's quartet from 2009, and the directorship and lead bandoneon chair of the Orquesta Típica Alfredo Marcucci, the tango orchestra heard with the poet Horacio Ferrer on the DVD The Poet Of Tango (2010). The same biography cites a 2009 review in the Spanish magazine Cuaderno de Jazz that placed him among the three leading bandoneonists in Europe, and lists appearances at the Villa Celimontana Jazz Festival in Rome, the Gulf Jazz Festival and the Jarasum Jazz Festival in South Korea.

Iorio's music sits where tango nuevo meets jazz. His central reference is Astor Piazzolla, whose repertoire fills A Night In Vienna, three of the ten pieces on Nocturno and eight of the ten on Tango Nuevo Revisited. The records are not tribute albums in the narrow sense: the Nuevo Tango Ensamble describes its own approach as a merger of classical music, tango nuevo, Italian melody and jazz performance, and the duo's later albums lean on original compositions. Discogs files most of his core releases (Philology, Jazzhaus, Enja, ACT and the Puglia jazz sessions) under Jazz, some with Latin and Classical as second genres and Tango as the style tag.

His identity is a genuine hybrid, and it is stated plainly here: he is a classically trained pianist, a tango specialist and a jazz-circuit bandoneonist at once. The jazz side rests on his Enja and ACT records, his work with the jazz musicians named above, and coverage in jazz publications including All About Jazz. His own biography also cites Amadeus, Jazzit and Musica Jazz as having reviewed the ensemble's albums. Outside that circuit his credits include religious song collections, a pop record and tango orchestra work, which are listed in the discography but do not define his catalog.