Kaunitz should have become a clergyman when he was a boy, but he soon decided otherwise and studied law instead. During his career, he was Austria's ambassador in Turin, minister in the Austrian Netherlands during the absence of its ruler Prince Charles of Lorraine, he represented Austria at the Congress of Aachen and was ambassador in Paris.
His most important and extremely influential office was that of the chancellor of state and minister of foreign affair where he had Maria Theresia's full trust.
Thanks in large part to him, Austria entered a treaty with France (and later Russia and Sweden) against Prussia to win back Silesia, which Austria lost as a consequence of the Congress of Aachen.
He founded the Austrian Staatsrat ("Council of State") and worked towards the goal of subjecting the church to the state. He followed the thoughts of the Enlightenment and among his aims was also the better education of the commoners.
Although Joseph II generally shared such ideas, Kaunitz' influence grew less during Joseph's reign, even less when Joseph's brother Leopold II reigned, and he resigned his office at the accession of Francis II.