After 1945, Bulgaria had to operate within the Cold War division of Europe between the West (the USA and its allies) and the East (the USSR and its allies).This division took its most visible form in the rivalry of military-political alliances that pitted the North Atlantic Treaty Organization (NATO) against the Warsaw Pact. Bulgaria strictly followed the Soviet model and acted as the USSR's closest and most reliable ally in intra-bloc relations. This position provided Bulgaria with certain economic advantages.

Bulgaria’s location in Southeastern Europe determined the Balkan orientation of the country’s foreign policy. Initially, Bulgaria’s main role was to monitor and counter Greece and Turkey, which had been brought into NATO in 1952. After the death of the Soviet leader Joseph Stalin in 1953, East-West tensions eased, and in the 1960s many of the contentious issues between Bulgaria and Greece and Turkey were resolved. From then on, the greatest source of tension for Bulgaria was with Yugoslavia over Macedonia, a region that was claimed by those two countries and Greece. Bitter disputes and hostility between Bulgaria and Yugoslavia ensued over the matter in the 1970s and 1980s. Even so, Bulgaria overall had peaceful ties with all Balkan countries and by the 1970s had become a stabilizing influence in the Balkans. Bulgaria actively participated in the Helsinki process and became an ardent supporter of the idea of a Balkan Nuclear Weapon-Free Zone. In the mid-1980s, however, Bulgaria’srelations with Turkey deteriorated amid a crackdown against the ethnic Turkish minority in Bulgaria. In 1984-1985, Todor Zhivkov’s regime embarked on a forced changing of names of the Bulgarian Turks, which was widely condemned by the European and international community.

The collapse of the colonial system in the 1960s established Bulgaria as one of the important economic and political partners of the newly independent states in North Africa and the Middle East. Relations with the Arab world were especially important. Bulgaria's interests became unduly concentrated in countries such as Libya and Iraq, whereasties with the rapidly industrializing countries of Southeast Asia were meager. The main instruments of Bulgarian foreign policy vis-à-vis Third World countries were ideological support and weapons supplies. Bulgaria's economic relations with the Third World were marred by the weaknesses of Bulgaria’s centrally planned economy, which characterized the whole Soviet bloc.

In Europe outside the Warsaw Pact, Bulgarian foreign policy was primarily directed toward the Federal Republic of Germany. The motives were mainly economic, but they also had a more general political undertone - to strengthen West German perceptions of Bulgaria as the center of the Balkans. In East Asia, Bulgaria worked to develop trade and economic ties with Japan. Some officials in Sofia viewed the “Japanese economic miracle”as an example and model for Bulgaria.

Throughout the Cold War, Bulgarian foreign policy adhered to the general line of the Eastern bloc, seeking external support primarily from the Soviet Union. The emergence of far-reaching reforms in the USSR under Mikhail Gorbachev’s “perestroika”and “glasnost” in the latter half of the 1980s induced the Bulgarian government to moderate its policies. Slowly and discreetly, Sofia began to look for opportunities to institutionalize contacts with the European Economic Community and to forge better relations with the United States.