From the age of 16, Biret played as a soloist with the most distinguished orchestras in the world including the London Symphony, the Philharmonia, the London Philharmonic, the Boston Symphony, the Leningrad Philharmonic, the Leipzig Gewandhaus, the Dresden Staatskapelle, the Orchestre de la Suisse Romande, the Tokyo Philharmonic, the Warsaw Philharmonic, the Orchestre National de France and the Sydney Symphony. She collaborated with eminent conductors such as Hermann Scherchen, Pierre Monteux, Erich Leinsdorf, Rudolf Kempe, Gennady Rozhdestvensky, Aaron Copland, Rafael Frühbeck de Burgos, Charles Mackerras, Jean Fournet, José Serebrier, Moshe Atzmon, Antoni Wit and Hiroyuki Iwaki. Biret also gave concerts at the festivals of Berlin, Montreal, Istanbul, Dubrovnik, Montpellier, Nohant, Persepolis, Royan and Athens. Idil Biret had her US concert premier at Symphony Hall in Boston under Erich Leinsdorf on Friday, November 22, 1963. Just before she was to play (Rachmaninoff Piano Concerto #3), Maestro Leinsdorf addressed the audience, saying that "we have just heard on the wireless that the President of the United States has been the victim of an assassination!" After the audience got over the shock, the orchestral management and players agreed to proceed with Miss Biret's performance.