Elay Kadosh grew up in Tel Aviv, the middle of the three brothers who play together as The Kadosh Brothers, and he came to the double bass through a record rather than through the family band. His own biography for the America-Israel Cultural Foundation dates it precisely: at thirteen he heard a Paul Chambers record and took up the instrument. The family's booking agency puts the age at eleven and does not name a record, which is the looser of the two accounts and the one that circulates more widely.

He went through the music track at the Tel Aviv Municipal High School A, School of Arts, the school Israelis call Ironi Alef, and through the Israel Conservatory of Music in Tel Aviv, as all three brothers did. Alongside that he studied privately with two bassists from opposite ends of the profession: Barak Mori, one of the busiest bass players in Israeli jazz, and Eli Magen of the Israel Philharmonic Orchestra. The classical and jazz halves of that training are audible in what he plays now, and the pairing is a recognisable Israeli pattern. Avri Borochov studied with Magen too, a generation earlier.

The credentials came in a run. In 2015 he won a place and a scholarship on the young musicians' workshop at the Red Sea Jazz Festival in Eilat. The America-Israel Cultural Foundation gave him excellence scholarships three times between 2016 and 2021. In 2018 he took the ALMA competition's prize for outstanding jazz player. The Israel Defense Forces assigned him to its Excellence Program, the status reserved for a small number of musicians each year, for his military service. Then two American acceptances landed at once in 2020: the Jazz Aspen Snowmass Academy, the full-scholarship summer program JAS runs with the Frost School of Music at the University of Miami under the artistic direction of Christian McBride, and The New School's jazz program in New York, also on a full scholarship. JAS's own alumni page files him in its 2021 student class rather than its 2020 one.

Before he left he was already leading his own bands in Tel Aviv, which is the part of his record that the family band's publicity leaves out. Guga Brenner, the bar on Brenner Street, ran two of them within six weeks in the spring of 2021: the Elay Kadosh Quartet on April 27, with Asaf Harris on saxophone, Nitsan Kolko on piano and Alon Benjamini on drums, and the Elay Kadosh Trio on June 1, with Kolko again and Roni Kaspi on drums. Both were billed under his name, both were standard jazz instrumentation, and the personnel is not incidental: Harris went on to record two albums for Ubuntu Music, Benjamini took the drum chair on Yuval Cohen's ECM date, and Kaspi has since built an international career of her own.

He finished the BFA in bass at The New School in the spring of 2024, playing his senior recital on April 22 of that year, and moved back to Israel. Between New York and Tel Aviv he has one credited recording of any kind, and it is not a jazz record: the Tel Aviv stoner and doom metal band Love Your Witch brought both him and his brother Onn Yosef in to write and play a brass and low-strings arrangement for the EP The Endless Rider, released on Reality Rehab Records on November 22, 2022, where his credit reads "Brass Arrangement, Double Bass" beside a trombone, a trumpet and a French horn.

Since returning he has held the double bass chair in The Kadosh Brothers full time, with Onn Yosef Kadosh on oud and Elamar Kadosh on drums and percussion. The trio's only released recording is still the single "Jirjur," issued July 17, 2025 and co-credited to Aquarium, the live concert series the Israeli national lottery's culture fund runs. They recorded a debut album in the summer of 2025, and as of September 2026 it has not appeared on any streaming service. The performing schedule has been the more visible half: Beit Barakat on Gaza Street in Tel Aviv on February 5, 2026, a first appearance at Shablul Jazz Club, the Jerusalem Jazz Festival's Blue Forest stage in the Israel Museum's sculpture garden on June 11, 2026, the sunset series at Jaffa Port on June 30, and a billing on the 40th Red Sea Jazz Festival in Eilat, November 11 to 14, 2026, as guests in the pianist Shlomi Shaban's set.

The bass line Elay Kadosh plays in The Kadosh Brothers has to do two jobs that are not usually asked of the same player: hold a jazz rhythm section together with no piano or guitar in the room, and follow an oud through maqam material where the melody is microtonal and the harmony is not going where a standard would take it. The Jerusalem Jazz Festival's own copy for the trio describes the result as a conversation between oud, double bass and drums, and Israeli bookers have settled on the same two-part description of the band's sound: the technical foundation of players raised in conservatories, laid over Arabic classical repertoire and progressive rock structure. Chambers is the stated starting point, and the choice of a hard-bop bassist as the first model rather than a contemporary one shows in a player who anchors rather than solos. What his own 2021 bands suggest, and what the family trio does not show, is a straight-ahead jazz musician: quartet with tenor, piano and drums, trio with piano and drums, both under his own name, both in a Tel Aviv jazz room.