Born in 1915, he was a member of an Austro-Hungarian noble family. His paternal grandfather had been governor of Dalmatia, his father consul in Jeddah. Tončić-Sorinj studied law and, during World War II taught languages in an air intelligence unit of the Wehrmacht.
In 1945, Tončić-Sorinj became chairman of the political department of the Austrian Institute for the Economy and Politics in Salzburg, and he joined the newly created ÖVP. Later he was member of the Austrian UNESCO commission and of the Austrian delegation to the advisory convention of the Council of Europe. From 1949 to 1966, he was member of the National Council of Austria for the ÖVP, from 1966 to 1968 he was foreign minister in the Josef Klaus government. From 1969 to 1974, he was secretary general of the Council of Europe.
In 1992 he decided to take the Croatiancitizenship because of his family connections to Dalmatia, but as a result he lost the Austrian one. With help from his political party, he became an Austrian citizen again.
