After the war, Kirchschläger worked as a district judge until 1954 in Langenlois and later Vienna. In 1954, he got the chance to work in the Ministry of Foreign Affairs, although he did not speak any foreign languages. In order to take part in the negotiations on the Austrian State Treaty, he taught himself English in only a few months. From 1967 until 1970, he was ambassador in Prague. Despite orders not to do so, he issued exit visas to Czech citizens who tried to flee from the Communists during the Soviet invasion of Czechoslovakia. From 1970 to 1974 he was Minister of Foreign Affairs.