Cornelius During was born into a family of musicians in Bielefeld and received his first lessons on the violin at the age of five, later on the viola. This was followed by admission to the Deutsche Streicherphilharmonie, schooling at the C.-Ph.-E.-Bach Musikgymnasium in Berlin and studies in orchestral conducting/viola at the Hochschule für Musik Franz Liszt Weimar. His studies with Nicolás Pasquet, Martin Hoff and Anthony Bramall were rounded off by lessons and master classes with Gunter Kahlert, Tomás Koutnik, Morten Wensberg, Tim Redmond, Mark Heron and Jorma Panula.

He has worked as a conductor since 2012. The winner of the 2nd Atlantic Coast International Conducting Competition in 2016 has been a guest on the podium of the Jenaer Philharmonie, the Philharmonie Baden-Baden, the Berliner Symphoniker, the Loh Orchester Sondershausen, the Philharmonie Teplice and the MDR- Sinfonieorchester Leipzig. He also assisted in opera productions at the Leipzig Opera, the Teatro Lirico di Cagliari, the Kiel Theater and the Dresden Semperoper.

Cornelius During is also a sought-after orchestral musician as a violist. In addition to a busy temporary schedule in various Berlin orchestras, he has been a member of the Berliner Operngruppe for a number of years, their recording of Mascagni's opera Iris was nominated five times for the Opus Klassik.

From  2012 to 2022, Cornelius During was chief-conductor of the Studentenorchester Münster, a 90-piece semi-professional ensemble. A recurring element of this long-standing collaboration were the regular children's concerts with concert pedagogue Dr. Ulrike Schwanse. Joint highlights were the performance of Giuseppe Verdi's Stabat Mater with the Landesjugendchor NRW, the live setting of the silent film classic Ich möchte kein Mann sein (I don't want to be a man), and the world premiere of Shir-Ran Yinon's Headbanging Symphony for orchestra and metal band.