Petros Klampanis was born July 15, 1981, on the Greek island of Zakynthos, growing up surrounded by Greek folk traditions that would later resurface, transformed, in his own jazz writing. He first enrolled at the Polytechnic School in Athens to study mechanical engineering, but the pull toward music won out. In 2005 he left Greece for the Amsterdam Conservatory in the Netherlands to begin formal jazz bass performance studies, and in 2008 he completed his training at the Aaron Copland School of Music at Queens College in New York City — the move that put him inside the city's working jazz scene rather than just its schools.

Once in New York, Klampanis found work quickly among musicians well outside his own generation's usual circuit: saxophonist Greg Osby, pianist Jean-Michel Pilc, and drummer Ari Hoenig among the earliest. It was the relationship with Osby that mattered most for his own name — Osby's Inner Circle Music released Klampanis's debut as a leader, Contextual, on April 18, 2011. The album is built as a kind of extended essay on what a double bass can be asked to do: on tracks like "Basscope" and "Blue Cave," Klampanis overdubs himself into a one-man "double bass orchestra," and elsewhere he reframes the instrument as lead voice behind a guest vocal, including a version of the Beatles' "Blackbird" sung by Gretchen Parlato. Veteran Norwegian bassist Arild Andersen called it "one of the most exciting projects I have heard from a bass player in years," a strong notice for a debut from a virtual unknown.

Minor Dispute followed on Inner Circle Music in 2015, again built around Klampanis's own compositions plus a small run of covers (Jobim's "Luiza" among them), scored for a chamber-adjacent lineup of cello, viola, and violins alongside a working jazz rhythm section — pianist Jean-Michel Pilc, drummer/percussionist John Hadfield, and, notably, guitarist Gilad Hekselman, who is credited as both a performer and a co-composer on the record. NPR named it one of the year's best jazz recordings, citing its integration of string arrangements and Eastern Mediterranean melody into a genuinely jazz-functioning ensemble rather than a jazz-plus-strings novelty.

2017's Chroma, his Motéma Music debut (released in Greece under license through Minos-EMI), pushed the strings-and-rhythm-section format further, adding a full small string ensemble around a core band of Shai Maestro on piano, Gilad Hekselman on guitar again, and John Hadfield and Keita Ogawa on drums and percussion. DownBeat's Jeff Potter praised the strings as "organic and equally vital" rather than decorative, and singled out Hadfield's drumming for its "sensitive, yet infectiously grooving" support. The record went on to win Best Live Album at the 2017 Independent Music Awards. Irrationalities (2019, Enja/Yellowbird) scaled back to a piano trio — Kristjan Randalu on piano, Bodek Janke on drums — Klampanis's second crowdfunded record and his first release for the German label Enja; it swept three categories at the 2020 Independent Music Awards, including Jazz Producer for Klampanis's own production work.

Klampanis's collaborative life runs in close parallel to his work as a leader. Since 2015 he has been the bassist of choice for Israeli tenor saxophonist Oded Tzur's working quartet, appearing on every one of Tzur's albums from the Yellowbird-era Like a Great River (2015) and Translator's Note (2017) through the ECM run — Here Be Dragons (2020), The Lion Turtle and Isabela (both 2022), and My Prophet (2024) — alongside pianists Shai Maestro and later Nitai Hershkovits, and drummer Ziv Ravitz. That same circle of players resurfaces throughout Klampanis's own catalog: Maestro appears on Chroma, Hekselman on both Minor Dispute and Chroma, and Ravitz on drums for Tora Collective (2023) and Latent Info (2025). Outside the jazz world proper, he has recorded and toured with vocalist and composer Arooj Aftab, contributing to Vulture Prince (2021), the live album Live In London (2023), and Night Reign (2024), including a 2025 BBC Proms appearance. His own site's bio also credits stage and studio time with Anoushka Shankar and members of Snarky Puppy, though those connections are more loosely documented than the Tzur and Aftab work.

During the pandemic Klampanis founded his own label, ΠΚmusic (PKmusik), and used it to release a run of standalone singles between 2020 and 2021 — "Coração Vagabundo," "Retrograde" (featuring Greek pop singer Katerine Duska), "Erotiko," the three-part "Τέττιξ" EP, "Regarding The Moon" (with baritone saxophonist Andrew Hadro), and "With Marco" — several of which fed into 2021's Rooftop Stories, another solo-overdub bass record recorded in Athens during the same stretch. Tora Collective (2023, Enja) turned outward again, drawing on Greek clarinet, oud, and voice alongside jazz personnel, and won Germany's Preis der Deutschen Schallplattenkritik. Latent Info (2025, Enja/Yellowbird), a return to piano trio with Randalu and Ravitz, explores what the label describes as the tension between sound and silence, paired with a companion live EP recorded by the sea on his native Zakynthos. He has also lent his name to the classical side of the Greek new-music scene, contributing to the 2021 Naxos anthology Roots - 21st Century Greek Music for Guitar, and a 2026 duo/trio project, Petrichor, with trumpeter Andreas Polyzogopoulos.

Klampanis now splits his time between New York and Athens and is an Associate Professor at Berklee College of Music, in addition to guest-lecturing at Oberlin Conservatory and Greece's Ionian Academy of Music. Bass Player magazine has called him a "bass ace," and DownBeat, JazzTimes, and Bass Musician Magazine have all singled out the combination of technical command and compositional ambition that runs through his catalog as a leader.

Klampanis writes at the intersection of the New York jazz mainstream and the Greek and broader Mediterranean/Balkan folk material he grew up around — not as a surface flavor added to standard jazz forms, but as a structural source of melody and rhythm, often scored for strings alongside a working rhythm section. His years playing under saxophonist Greg Osby and pianist Jean-Michel Pilc shaped his time inside a band; his own records extend that vocabulary toward chamber-jazz instrumentation, spoken and sung Greek-language material, and, in his solo-bass work, an "orchestra of one" built from overdubbed double bass. As a sideman, his long tenure in Oded Tzur's quartet and his work with Arooj Aftab show the same instinct for supporting harmonically adventurous, texture-first music without crowding it.