The early 1970s brought fundamental transitions in international scientific collaboration that significantly affected the international relations in global patterns that are still relevant today. This article uses a multi-perspective approach to argue that the underlying condition for the globalization of science diplomacy was the increasing participation of recently independent countries in international technoscientific affairs, examining critical research areas, including space exploration, oceanography, nuclear technoscience, the environmental sciences, and health and population studies. Themes emerged at that time that continue to characterize what we term ‘Global Science Diplomacy’: multipolarity, resistance and agency, lack of global consensus, regional alliances and interests, and the centrality of the United Nations system to the conduct of transnational science. This survey is a first step in historical reflection on this phenomenon and shows that it was the emergence of the Global South in Science Diplomacy affairs that made Science Diplomacy global at the beginning of the 1970s.