Born in Nuremberg, Altus Matthias Rexroth studied at the University of Music in Karlsruhe, the Schola Cantorum Basiliensis, with Marilyn Horne and Ruth Falcon in New York as well with Eytan Pessen at the Stuttgart State Opera, where he made his operatic debut in Purcell's King Arthur. He was the only countertenor to win two of the most prominent international singing competitions: the 37th Francesco Viñas Competition in Barcelona, where he was also named best countertenor, and the 19th Hans Gabor Belvedere Competition in Vienna, where he was also awarded eight special prizes. He went on to become a Rising Star of the Cologne Philharmonie and has since been considered one of the most sought-after male Altos within this rare fach.

As a concert singer, Matthias Rexroth enjoyed a close collaboration with Nikolaus Harnoncourt, under whose direction he was heard in Handel's Jephtha and Theodora, as well as Purcell's Ode to St Cecilia, at the Vienna Musikverein and the Styriarte festival in Graz. Other career highlights include his debut with the Vienna Philharmonic under Riccardo Muti, concerts with the St Petersburg Philharmonic under Yuri Temirkanov, with the Orquesta Sinfónica y Coro Radio Televisión Española, the Frankfurt Museum Orchestra under Paolo Carignani, and appearances with the Accademia di Santa Cecilia in Rome and the Orchestra del Teatro di San Carlo in Naples under Fabio Luisi and Nicola Luisotti. At the Rossini Festival Bad Wildbad, he sang the world premiere of Wolfgang Rihm's KOLONOS, two Hölderlin/Sophocles fragments, a piece composed especially for him.

The artist's opera productions are numerous: Handel's Giulio Cesare at the Norske Opera Oslo, Ottone and Admeto at the Handel Festival Halle, Oberon in Britten's A Midsummer Night's Dream, and Prince Orlofsky in a new production of Johann Strauss' Die Fledermaus at the Aalto Theater Essen under Stefan Soltesz. Matthias Rexroth also sang in Telemann's Der geduldige Sokrates under René Jacobs at the Innsbruck Festival and at the Staatsoper Berlin, created the title role in Gluck's Ezio, Ottone in Monteverdi's L'Incoronazione di Poppea at the Staatsoper Hamburg, Athamas in Handel's Semele at the Aalto Theater Essen, Hasse's Marc'Antonio e Cleopatra at the Kissinger Sommer, the Handel operas Partenopeand Rodelinda at the Theater an der Wien, and Ozia in Almeida's La Giuditta at the Frankfurt Opera, where he subsequently enjoyed success as Tolomeo in a new production of Handel's Giulio Cesare and as Arcane in Handel's Teseo.

At the Semperoper Dresden he appeared in new productions of Henry Purcell's King Arthur as well as in Martini's L'impresario delle Canarie. This was followed by a new production of Cesti's L'Orontea at Oper Frankfurt, Britten's A Midsummer Night's Dream at Musiktheater im Revier Gelsenkirchen, a revival of Handel's Giulio Cesare at Oper Frankfurt, and the German premiere of Cavalli's "dramma per musica" Veremonda, L'Amazzone di Aragona at the Schwetzingen Festival.

Matthias Rexroth has also given numerous concerts and recitals, appearing in Schnittkes Faust Kantate with the Radio Symphony Orchestra Vienna under Wladimir Fedossejew and, as part of a European tour of the Akademie für Alte Musik, in Bach's Mass in B minor under Pierre Cao. The same piece, together with Bach’s St. John Passion he performed frequently with the Gewandhaus Orchestra Leipzig while at the Bachfest Leipzig he sang Handel's Messiah in Mozart’s transcription.

Performing a central figure in his repertoire, the "Swan" in Carl Orff's Carmina Burana, Matthias Rexroth was recently heard with several orchestras, including the Malaysian Philharmonic Orchestra under Roberto Abbado, Vienna Symphonic under Rafael Frühbeck de Burgos at the Vienna Musikverein, the Danish National Symphony Orchestra under Fabio Luisi, with the Orchester des Teatro San Carlo in Neapel under Donato Renzetti as well as the City of Birmingham Symphony Orchestra and the Orchestre Philharmonique de Monte-Carlo under Kazuki Yamada, under whose baton he also made his debut at the BBC Proms at London's Royal Albert Hall. In the season 2023 - 2024, Matthias Rexroth took on the role once again with the Orchestre National de France at the Théâtre des Champs-Élysées in Paris.

As a guest lecturer, Matthias Rexroth regularly shares his experience, knowledge, and vocal technique at international master classes. These have taken him to places such as New York, San Francisco/USA, Mexico City, Puebla and Saltillo/Mexico, Santiago de Chile/Chile, Kyoto/Japan, Daegu/South Korea, Kuala Lumpur/Malaysia, Moskau, Novosibirsk und St. Petersburg/Russland, Jinan, Tsingtao und Peking/China, Warsaw, Wroclaw/Poland, Kaunas/Lithuania, Reims, Paris/France, Vienna, Graz/Austria, Haifa, Tel-Aviv, Jerusalem/Israel as well in Germany in Stuttgart, Karlsruhe, IMA Neumarkt and Frankfurt.