Born in South Africa and studied at the University of Pretoria where she received her vocal training with Dr Mimi Coertse and was a member of the Black Tie Opera Studio.
Johanni van Oostrum is in demand as interpreter of leading roles by Strauss, Wagner, Janáček and Mozart. Performed in such theatres as Bavarian State Opera, Komische Oper Berlin, Theater an der Wien, Dutch National Opera, Royal Swedish Opera, Théâtre des Champs-Élysèes in Paris, Gran Teatre del Liceu, Graz Opera; appeared at music festivals in Aix-en-Provence and Munich, and at such concert halls as Barbican Centre in London, Concertgebouw Amsterdam, BOZAR in Brussels ecc.
She has worked with conductors such as Sir Simon Rattle, Alan Gilbert, Ivor Bolton, Yannick Nézet-Séguin, Adam Fischer, Antonello Manacorda, Oksana Lyniv, Bertrand de Billy and Laurence Equilbey as well as with directors such as Harry Kupfer, Barrie Kosky, Tobias Kratzer or Vera Nemirova.
In 2015, she made her debut at the Bolshoi Theatre as Marschallin (Der Rosenkavalier).