The article provides a comparative review of the national nanotechnology initiatives in the largest emerging economies (Brazil, Russia, India, China, and South Africa - BRICS). It focuses on the influential role of state action, the evolution of the initiatives, institutional aspects, and a brief comparison of recent scientific production among the countries. Understanding the context of each country's nanotechnology STI policy is essential for comprehending the scope and the primary challenges faced in developing these programs and initiatives. The methodology involved rigorous bibliographical and documentary research, analysis of scientific production indicators, and the estimation of a nanotechnology Activity Index. The political and institutional complexity and socioeconomic adversities in emerging countries are challenging obstacles to promoting emerging technologies. Government perspectives and their role as technology inducers or fosterers significantly differ among countries, even when they are institutionally similar. Overall, the main nanotechnology initiatives in the BRICS countries have historically been led by the state, resulting in significant scientific advancements but limitations on the potential for innovation outcomes. Alongside institutional heterogeneity in the formulation and implementation strategies, geopolitics plays a crucial role in the initiatives' trajectory, especially in countries vying for international leadership against Western powers.