Jonke was born and educated in Klagenfurt, Austria. He attended the Gymnasium (university preparatory school) and the Conservatory. After he served his mandatory military service, he continued his studies at the College of Music and Representative Art in Vienna in the Film and Television Department. He did not, however, complete his studies there, nor his studies of History, Philosophy, Music Theory, or German Studies at the University of Vienna which followed. Despite this, in 1971 he received a scholarship to study in West Berlin, where he stayed for five years. He then lived for a year in London, followed by extensive travels through the Middle East and South America, after which he settled again in Austria.
Jonke died of cancer at the age of 62 on 4 January 2009 in Vienna. He was given a grave of honor ("Ehrengrab") in the Zentralfriedhof, the central cemetery in Vienna.