Austrian diplomat and foreign minister who played a leading role in the Third Partition of Poland (1795) and the negotiations of several treaties with Napoleonic France. He was the cousin of Philipp, Graf von Cobenzl, an Austrian chancellor.

A protégé of the Austrian chancellor Wenzel Anton von Kaunitz, Cobenzl became minister at St. Petersburg in 1779. At the Third Partition of Poland (Poland, Partitions of) in 1795, he gained sizable territories for his country in compensation for Austria's exclusion from the Second Partition. At the peace negotiations with France at Campo Formio (1797), Rastatt (1797–99), and Lunéville (1801), the Holy Roman Empire lost the left bank of the Rhine to France. As foreign minister from 1800, Cobenzl, attempting to relieve tensions with France, recognized Napoleon's imperial title in 1804 but nevertheless became embroiled in the War of the Third Coalition (1805), in which Napoleon again defeated Austria. Cobenzl was dismissed a few weeks after the disastrous Battle of Austerlitz in 1805.