Karl Maximilian, Prince of Dietrichstein (Karl Maximilian Philipp Franz Xaver; 28 April 1702 – 24 October 1784), was a German prince member of the House of Dietrichstein, 6th Prince (Fürst) of Dietrichstein zu Nikolsburg, Princely Count (gefürsteter Graf) of Tarasp, Baron (Freiherr) of Hollenburg, Finkenstein and Thalberg.
Born in Brno, he was the eighth child and third (but eldest surviving) son of Walther Franz Xaver Anton, 5th Prince of Dietrichstein, by his second wife, Countess Karolina Maximiliana Pruskovsky von Proskau.