foreign minister of Austria-Hungary (1916–18), whose efforts to disengage his country from its participation in World War I failed to prevent the dissolution of the Habsburg monarchy in 1918.

Czernin, born into the Czech aristocracy, entered the Austro-Hungarian diplomatic service in the Paris embassy (1895) and was later chargé d'affaires at The Hague (1899). In 1903 he entered the Bohemian Landtag (provincial assembly), where he became an exponent of conservative causes. A close adviser of Archduke Francis Ferdinand, he opposed the introduction of universal suffrage to Austria (1907) and worked to restore political power to the aristocracy. Accorded lifetime membership in the Austrian Empire's upper chamber (1912), he was recalled to the diplomatic service in 1913 as minister to Romania, where he served for three years.

With the accession of the new emperor Charles I (1916), Czernin was appointed foreign minister for Austria-Hungary (December 1916). His plans for extricating Austria swiftly from World War I were wrecked by Germany's opposition and the military and economic entanglements of the Central powers. His standing as foreign minister was severely shaken by the territorial concessions to the newly independent Ukraine at the Brest-Litovsk (Brest-Litovsk, treaties of) peace negotiations (February 1918), and he fell from office over the Sixtus Affair (April 1918), an Austrian-Allied secret negotiation of which his emperor had not kept him fully informed. He was a member of the national assembly (1920–23) during the early years of the Austrian republic.