The young Croatian baritone Leon Košavić completed his master's degree at the Music Academy in Zagreb in the singing class of Giorgio Surian, which lead to a membership of the Queen Elisabeth Music Chapel program under the direction of José van Dam.

In 2011 he began his musical career as Papageno at the Croatian National Opera, where he sang Masetto and Moralès and Malatesta in the following years.
In 2015 he made his debut at the Finnish National Opera as Malatesta (Don Pasquale). In the same year, Košavić won the Croatian Theatre Prize for "outstanding performances by young artists under 30" for his sensational performance of Don Giovanni.

This was followed by important prizes for young singers at the Emmerich Smola Förderpreis, the Mirjam Helin International Singing Competition and the Stanislaw Moniuszko Competition.

 Since then he has appeared at numerous European opera houses such as the Royal Opera House London (Ping in Turandot), Stuttgart State Opera (Don Giovanni), Liège (Figaro in Nozze di Figaro and Guglielmo in Cosi fan tutte), Antwerp (La Juive & Ariadne auf Naxos), Lausanne (Masetto in Don Giovanni) and Strasbourg (Figaro in Barbiere di Siviglia).

He was a member of the ensemble at Theater St. Gallen, where he sang Pagageno (Magic Flute) and Germont (La Traviata).

 An intensive concert activity with the conductor Nathalie Stutzmann also took him to the Elbphilharmonie Hamburg, Liverpool, Sao Paolo, Bergen, Paris and London. Moreover, he has given concerts with the European Union Youth Symphony in the Konzerhaus Berlin and at the Grafenegg Festival.

 Projects in the current season include his debut at Grand-Théâtre de Genève in La Juive, Masetto (Don Giovanni) with Riccardo Muti at Teatro Regio Torino, Papageno (Zauberflöte) at Royal Opera House London and concerts with the Atlanta Symphony Orchestra, as well as his debut at Opernhaus Zürich as Ottokar (Der Freischütz).