Seydewitz is a surname. Notable people with the surname include:
Carl Christian Seydewitz (1777–1857), German-Danish portrait painter and officer
Ernst von Seydewitz (1852–1929), Saxon politician and saxon finance minister Max Seydewitz (1892–1987), German politician (SPD, SAPD and SED) Otto von Seydewitz (1818–1898), Prussian politician, member of Reichstag