His musical carreer began very early. At the age of seven, he began playing piano and flute, turning to singing on Pop- and Rockfestivals with twelve. Since then he was engaged in theater projects through Germany and composed his first songs. He had his first contact with opera at the age of 17 when he sang Colas in Mozart's Bastien and Bastienne. For him all types of music had been always something universal but after his graduation from Highschool he concentrated more on classical singing.
In addition to his studies in history, philosophy and music, he studied singing at the Musicacademie of Cologne with Professor Lieselotte Hammes and KS Kurt Moll.

From 1996 on he had his first fixed engagements in Regensburg (1996-1998) and Darmstadt (1998-2000), where he sang Roles as Scarpia in Puccinis Tosca, Amonasro in Aida, Germont in La Traviata and many modern pieces like Manfred Trojahns Enrico, Alfred Schnittkes Life with an Idiot or Friedrich Cerhas Der Rattenfänger in which he played as well at the Wiener Festwochen.

In 2002, he made his debut at the Bavarian State Opera with the role of Peter in Humperdincks Hänsel and Gretel and since then he was a regularly guest at this house with roles like Borromeo in Pfitzners Opera Palestrina, Telramund in Lohengrin, his interpretation of Wotan and Wanderer in Andreas Kriegenburgs Ringcicle and as Mandrika in Richard Strauss‘ Arabella.

In 2004, Thomas Johannes Mayer gave his first well-respected wotan in the Valkyrie and then throughout the Ring Cicle at the Badisches Staatstheater Karlsruhe.
From 2004 to 2006, he was a member of the Theater Basel with roles like Don Giovanni, Eisenstein (Fledermaus), Melot, Kurvenal, (Tristan und Isolde), Mercucio (Romeo et Juliett/ Gounod)) and Wozzeck before he performed 2007 Achilles in the production of the Year Award- winning version by Othmar Schoecks Penthesilea directed by Hans Neuenfels.

Also in 2007 he was able to convince as Wozzeck at the Scala in Milano, where he successfully came back in 2009 for the role of Posa in Verdis Don Carlos.

From 2008 to 2010, he was engaged at the Stateopera of Hamburg where he performed Mandrika, Rigoletto and Telramund and refixed in his short-term entry into the premiere of the Valkyrie.
In 2012, he made his debut at the Bayreuther Festival as Telramund in Hans Neuenfels legendary Lohengrin, conducted by Andris Nelsons.

In the following years the singer was also to be seen in Bayreuth as Flying Dutchman (2015) and as Wanderer in Siegfried (2017). Followed in 2018 by the Amfortas in Parsifal and in 2019 again by Telramund under the musical direction of Christian Thielemann.

In 2015 he successfully designed the title role of Moses in Schönberg's opera Moses and Aron at the Opera National de Paris where he could as well succeed with Wotan, Wanderer, (Ring), Thoas in Iphigenie en Tauride, Misguir in Snegurotschka from Rimsky-Korsakof and Vodnik in Dvoraks Rusalka.
In 2016, Thomas Johannes Mayer made his debut at the Vienna State Opera with Telramund in Lohengrin. This was followed in 2017 by the Wotan and the Wanderer in Richard Wagner's Der Ring des Nibelungen". In 2019 he sang the title role in Manfred Trojahn's opera Orest. As well he gave Amfortas in Parsifal under the direction of Valery Gergiev, followed by Don Pizarro in Fidelio.

In the season 2020, he was seen as Pizarro in Beethoven's Leonore.
Futhermore, Thomas Johannes Mayer has been and is regularly guest at major opera houses such as the Royal Opera House Covent Garden, the Berlin State Opera, the Deutsche Oper Berlin, the Staatsoper Dresden and the Opera Leipzig, the Staatstheaterand Operas in Hannover, Stuttgart, Wiesbaden, Cologne and Essen, the Theatre de la Monnaie Brussels, the Dutch National Opera Amsterdam, the Maggio Musicale in Florence, the New National Theater Tokyo, the Bregenzer Festival and the Salzburg Festival.

The singer's repertoire covers the most important parts of his domain: among others in the title roles of Don Giovanni (Mozart) Wozzeck (Berg), Macbeth, Rigoletto, (Verdi) Eugen Onegin (Tchaikovsky), The flying Dutchman (Wagner), Mathis der Maler (Hindemith), Moses (Schönberg) and Orest (Trojahn), as well as in over 90 leading roles such as Amfortas, Telramund, Hans Sachs (Die Meistersinger von Nürnberg), Kurwenal, Wotan/Wanderer, and Wolfram in Tannhäuser (Wagner), followed by Verdis Amonasro in Aida, Jago in Otello Germont in La Traviata and Posa in Don Carlo, Puccinis Scarpia in Tosca, Richard Strauss Barak in Frau ohne Schatten, Mandrika in Arabella, Jochanaan in Salome and Scarpia in Puccinis Tosca.

Besides, Thomas Johannes Mayer is engaged worldwide as a Lied- and concertsinger.
Mayer is in high demand as a “short-term Wotan jumper”. In 2009 he has saved the premiere of the Valkyrie in Hamburg and in 2012 the Valkyrie premieres in Paris and Munich, where he was attested by the critic Robert Braunmüller that he could become the hero -baritone of his generation.
He worked together with renowned directors such as David Alden, Stephan Braunschweig, Romeo Castelucci, Frank Castorf, Robert Carson, Willy Decker, Andreas Dresen, Achim Freyer, Götz Friedrich, Klaus Michael Grüber, Klaus Guth, Michael Hampe, Dietrich Hilsdorf, Andreas Homoki, Peter Konwitschny, Andreas Kriegenburg, Günther Krämer, Harry Kupfer, Uwe Eric Laufenberg, Christof Loy, Hans Neuenfels, Vera Nemirova, Friedrich Meyer-Oertel, Peter Stein, Michael Thalheimer, Dmitri Tscherniakow and Krzysztof Warlikowski.

Musically, Thomas Johannes Mayer was able to work with important conductors such as
Claudio Abbado, Daniel Barenboim, Semjon Bychkov, Dennis Russell Davies, Adam Fischer, John Eliot Gardiner, Daniele Gatti, Michael Gielen, Hartmut Haenchen, Mariss Jansons, Marek Janowski, Philippe Jordan, Vladimir Jurowski, Lothar Koenigs, Sir Neville Marriner, Zubin Mehta, Kent Nagano, Andris Nelsons, Kirill Petrenko, Sir Simon Rattle, Donald Runnicles, Ulf Schirmer, Stefan Soltesz, Christian Thielemann, Simone Young, Marcello Viotti, Mario Venzago, Sebastian Weigle and Jaap van Zweden and has performed concerst with the Berliner Philharmoniker, the Vienna Philharmonic, the Munich Philharmonic, the Gewandhausorchestra Leipzig and the Boston Symphony Orchestra.

A very big concern for Thomas J. Mayer is helping young singers to get familiar with the requirements of the particular difficultys of operasinging. He wants to pass his knowledge which he acquired on stage in more than 40 years. With the help of Asian philosophy, Tai-Chi and Chi Kung, he tries methodologically and didactically to bring body and soul of the singer together. Therefore he has founded the association "Gesamtkunstwerk Klang e. V.” where he is able to offer affordable Masterclasses and other events.