He graduated from the Faculty of Philosophy, University of Sofia (Bulgaria), and was a labour movement activist and a member of the Communist Party of Bulgaria (since 1918). In 1923, Karaivanov took part in unsuccessful the September Uprising, during which he was a member of the Revolutionary Committee, and a close associate of Georgi Dimitrov and Vasil Kolarov. After the failed uprising, he went to Vienna, where, together with Dimitrov and Kolarov, he was publishing the illegal newspaper Rabotnički vesnik. In the period 1926–1929, Karaivanov lived in the Soviet Union, where he worked at the Institute of Marx and Engels and, later, at the Communist University of the Workers of the East. From 1934 to 1944, Karaivanov was a member of the Comintern Executive Committee in Moscow. After the liberation of Bulgaria in 1944, he came to this Balkan country, but due to disagreements with some leaders of the Communist Party of Bulgaria, he moved to Yugoslavia where he obtained his citizenship. Karaivanov was a member of the Federal People’s Assembly of the Federal Republic of Yugoslavia, and at the Sixth and Seventh Congress of the Union of Communists of Yugoslavia he was elected for a member of the Central Committee of the Communist Party of Yugoslavia. Ivan Karaivanov was also the editor of the newspaper Glas Bulgara. He was awarded the Order of Heroes of Socialist Labour (1959), as well as with other foreign and Yugoslav decorations.