Johannes Grau, started his first musical experience and training at St. Thomas Boys Choir in Leipzig. Already as a boys soprano he collected solo experiences under Kurt Masur. He studied singing at the Academy of Music 'Hanns Eisler' - Berlin with Prof. Scot Weir and was a member of the Song class with Prof. Semyon Skigin. Further studies were carried out at the 'Conservatorio di Firenze', parallel to his studies in Berlin he attended the 'Conservatoire de Paris' under the direction of Prof. Yves Sotin. He participated in master classes with Peter Schreier and Dietrich Fischer-Diskau.

2013 he made his debut as 'Tamino' in Mozart's Magic Flute, conducted by Stefan Klingele, furthermore he took a tenor part in the new production 'Vom Ende der Unschuld' at "Kampnagel" in Hamburg, directed by Kirsten Harms.

In the seasons 2014-2016 Johannes Grau was employed in various productions at the Wuppertal Opera - with smaller roles in Tosca, Salome and Parsifal, as well as the tenor soloist in a scenic production of Bach's 'St. John Passion' under the direction of Jörg Halubek (music) and Philipp Harnoncourt (director).

In the spring of 2016 and 2017 Johannes Grau sang the 'Maler' in Alban Berg's opera 'Lulu', under the direction of GMD Toshiyuki Kamioka (Wuppertal) and GMD Timo Handschuh (Ulm).  The magazine "Opernglas" described his presentation as "particularly impressive" (issue 6/16) in the FAZ Eleonore Büning wrote “a youthful voice with a beautiful metallic timbre“.

Also in 2016 Johannes Grau made his debut as Nemorino in Donizetti's "L'Elisir d'amore" - Theater Ulm. Furthermore he sang the opera Königskinder, in the role of the Königsohn under the direction of GMD Sebastian Weigle. At the Easter Festival in Baden-Baden 2017 he sang the role of Don José in Carmen.

In 2018 he sang the role of Max in “Der Freischütz”.