Clam-Martinic was active in the Bohemian Lower House as well as in the Upper House as a speaker for the Conservatives. In 1892-1893 he accompanied Archduke Francis Ferdinand on his tour around the world and became the heir apparent's close friend.
Clam-Martinic served as a company commander on the Russian and Italian fronts from August 1914 to 1916, in the process moving ever closer to the House of Habsburg, and as a result more distant from Czechoslovakian nationalists. In October 1916, he became minister of agriculture under Minister-President Ernst von Korber. The new Emperor Charles in December 1916 appointed Clam-Martinic minister-president, and the Czech attempted to create a truly multinational cabinet. This endeavor failed owing especially to the opposition of the Czechs and Poles and in the process Clam-Martinic alienated the Austrian Germans; his appeal of May 1917, "Let us above all be Austrians!" fell upon deaf ears, and Clam-Martinic resigned his post on June 19, 1917, to become military governor of Montenegro for the duration of the war.