Peter Simonischek was developed at the Akademie für Musik und Darstellende Kunst in his native city Graz. After engagements in Graz, St. Gallen, Bern and at the Düsseldorfer Schauspielhaus, from 1979 on there followed a periode of 20 years as part of the esamble at the Berliner Schaubühne, where he worked with Peter Stein and direcorts like Luc Bondy, Andrea Breth, Klaus Michael Grüber and Edith Clever.
Since 1983 Simonischek peformed at the Salzburger Festspielen – he played in productions of Peter Stein, Axel Corti, Klaus Michael Grüber, Andrej Wajda and Dieter Dorn (name part of Goethes Torquato Tasso, 1982). Since the summer of 2002 Simonischek performed permanent the name part in Hofmansthals „Jedermann“ - For the last time in August 2009, after 99 performances. At the beginning of the season 1999/2000 Peter Simonischek became part of the ensemble at the Wiener Burgtheater, where he amongst others worked together with Andrea Breth, Peter Zadek, Thomas Langhoff, Andreas Kriegenburg and Anselm Weber and can be seen in different character parts, from Shakespeare, Ibsen, Horvath, Hofmannsthal, Albee to Nestroy.
In 2009 he gave a guest performance as Bassa Selim in the Teatro San Carlo in Neapel and as „Baumeister Solness“ at the Grazer Schauspielhaus.
Since the end of the senventies, Peter Simonischek performes constantly in cinema and TV – at last he played in „Hirankel“ by Hans Steinbichler – for this part he was was honored with the golden Grimme-Preis. For his performance in the comedy „Mit einem Schlag“ he was nominated for the Bayerischen Fernsehpreis.
2008 Simonischek was awarded with the german Hörbuch-Preis as the best interpreter.