He has performed on stage with the Glyndebourne Festival, Royal Opera House, Covent Garden, English National Opera, Theater an der Wien, Deutsche Staatsoper Berlin, Teatro all Scala Milan, Oper Frankfurt and Bayerische Staatsoper, with the Salzburg and Aix-en-Provence and Edinburgh festivals, and the BBC Proms. He has recorded extensively for the major labels and was nominated for a Gramophone Award. He won the Royal Philharmonic Society Singer Award, and is a Visiting Professor at the Royal Academy of Music.
In 2016 John Mark was diagnosed with Leukaemia. Fortunately this was an early diagnosis and with ongoing treatment the prognosis for his general health is very good. However, he has decided that it is time to retire from public performance. It is still very much his intention to remain involved with singing and performing through teaching, adjudication and master classes.