Mauro Ottolini was born in Bussolengo, near Verona, on April 14, 1972. He graduated with honors in trombone and trumpet from the Verona Conservatory in 1993, then spent twelve years in the orchestra pit of the Arena di Verona before turning to jazz full time. He went on to earn a jazz diploma from the Bonporti Conservatory in Trento, studying under pianist Franco D'Andrea, and later traveled to Los Angeles to study conch-shell performance with the American trombonist Steve Turre, a partnership that would eventually shape one of his own signature projects.

His debut as a leader, Ecologic Island (2005, Artesuono), paired his trombone, tuba and shells with tenor saxophonist and clarinetist Francesco Bearzatti, both credited as composers alongside drummer U.T. Gandhi. He followed it with two very different big-ensemble records in 2007: Ottovolante - Le Canzoni Del Varieta, a large swing and big-band arrangement of Italian variety-show songs featuring Daniele D'Agaro and Bearzatti among a dozen musicians, and Slide Family, co-led with fellow trombonist Beppe Calamosca and built entirely around a "trombone family" of slide instruments, electronics and loops, with drummer Zeno De Rossi and trombonist Giancarlo Schiaffini contributing electronics. In 2008 he co-led Gipsy Blue (Artesuono) with D'Agaro and accordionist Vincenzo Castrini, a chamber session with string-orchestra arrangements by Stefano Zavattoni.

Around 2008-2009 Ottolini founded Sousaphonix, the vehicle for his most sustained body of work: a shifting brass-and-reeds ensemble built around his sousaphone and trombone that explores polyphonic writing and unconventional instrumentation (theremin, toy instruments, live electronics). Sousaphonix released its self-titled debut in 2009, followed by The Sky Above Braddock (2010, CAM, guesting Antonello Salis and Giovanni Falzone), a second self-titled album on Jazzit Records (2012, with Danilo Gallo, Enrico Terragnoli and Giorgio Pacorig), Bix Factor (2012, Parco Della Musica Records, a Bix Beiderbecke-inspired project), Musica Per Una Societa Senza Pensieri (2015) and Buster Kluster (2016, Azzurra Music, Discogs-tagged Dixieland and Ragtime alongside Jazz), the last two reuniting a recurring core of Terragnoli, Gallo, Zeno De Rossi and reedman Dan Kinzelman. Meanwhile his own-name catalog continued with Degustando Musica (2009, with the group Licaones), the sextet session Secret Stories (2010, Artesuono, with D'Agaro, trumpeter Fulvio Sigurta, bassist Alessandro Turchet, pianist Bruno Cesselli and singer Maurizio Pagnutti), the solo-billed I Separatisti Bassi (2011), and the trio album Up & Down (2012, with D'Agaro and accordionist Simone Zanchini). He also recorded Heaven Sent (2013) with American trombonist Frank Lacy.

Ottolini's Top Jazz win as Italy's best jazz musician, awarded by Musica Jazz's national critics' poll in 2012, came in the middle of a decade of high-profile sideman work. He is a longtime member of Franco D'Andrea's small and large groups, credited on Traditions and Clusters (2012), the Franco D'Andrea Sextet's Monk and the Time Machine (2014), Three Concerts, Live at the Auditorium Parco della Musica (2015), Traditions Today (Trio Music Vol. III) (2017) and the Franco D'Andrea Octet's Intervals I and Intervals II (2018). He also toured and recorded repeatedly with trumpeter Enrico Rava, appearing on Jazzitaliano Live 2009, the ECM release Rava on the Dance Floor (2012, with the Parco della Musica Jazz Lab), My Songbook (2016) and the concert DVD Note Necessarie (2017, CG Entertainment, not to be confused with Rava's unrelated 2004 Minimum Fax audio anthology of the same title), and played trombone in Tino Tracanna's Acrobats on Red Basics (2016, Parco Della Musica Records, alongside guitarist Roberto Cecchetto, bassist Paolino Dalla Porta and drummer Antonio Fusco). In 2018 he was the sole horn in saxophonist Gavino Murgia's all-acoustic Blast 4tet, recording the Charles Mingus-opening album Blast (Abeat Records).

Ottolini's later projects turned toward concept records built around his instrumental research. Sea Shell - Musica Per Conchiglie (2019, Azzurra Music) is performed entirely on seashells gathered from oceans around the world, layered with field recordings and released with an ecological message supported by Greenpeace and Legambiente; it also became an animated short film. The same year he reunited with D'Agaro, this time joined by guitarist and producer Enrico Merlin, for Dick's Holler (2019, recorded years earlier in 2007 and issued through Merlin's own Alchemist Vault), and released The Lounge Lovers (2019, Azzurra Music) with the group Licaones and Bearzatti. In 2017 he had also released a large-scale tribute record, Tenco - Come Ti Vedono Gli Altri, reworking the songs of Italian singer-songwriter Luigi Tenco. His most recent leader album, Storyville Story (2020, Parco Della Musica Records), revisits the jazz of 1910s-1930s New Orleans in arrangements for a group including trumpeter Fabrizio Bosso, sousaphonist Glauco Benedetti, pianist Paolo Birro and vocalist Vanessa Tagliabue Yorke.

Alongside this jazz catalog, Ottolini has built an extensive freelance career as a trombonist and arranger for Italian popular music, appearing on records by Marco Mengoni, Davide Van De Sfroos, Vinicio Capossela, Patty Pravo, Malika Ayane, Daniele Silvestri and Sonohra, among others; this session work runs in parallel with, rather than in place of, his jazz identity. He teaches jazz improvisation and jazz trombone at the Conservatorio "Agostino Steffani" in Castelfranco Veneto, and his own biography states additional teaching engagements in the United States and Europe; those specific claims could not be independently confirmed and are reported here with that caveat. In 2019 a newly described sea-snail species, Turritella ottolinii, was named after him by Italy's Cupra Marittima Malacological Museum in recognition of his shell-based work.

Ottolini works at the intersection of New Orleans brass tradition and instrumental experimentation. His catalog runs from straight-ahead Dixieland and big-band variety arranging (Ottovolante, Storyville Story, the Discogs-tagged Dixieland and Ragtime styles of Buster Kluster) to the avant-garde and free-improvisation end of the spectrum, where Sousaphonix records bring in theremin, live electronics and toy instruments alongside conventional brass and reeds (Dick's Holler carries Discogs' Avant-garde Jazz and Free Jazz tags). His teacher Franco D'Andrea is a direct influence and a recurring bandleader in his own sideman work, and his study with Steve Turre gave him the conch shell as a signature solo voice, carried furthest on the all-shell album Sea Shell. Across both ends of that range, his own leader projects tend to be concept-driven: a "trombone family" ensemble, a Bix Beiderbecke tribute, a Luigi Tenco songbook, a New Orleans history lesson, an ecological shell record, each built around a single instrumental or repertoire idea rather than a fixed working band.