The article discusses the organizational evolution of the BRICS association in the context of a fundamental transformation of global political organization. The authors proceed from the premise that contemporary global politics is increasingly moving away from a purely hierarchical model toward a more complex, multicentric structure, in which network interactions between states, non-state actors, and their associations are beginning to play a key role. Within this approach, BRICS is viewed not simply as an economic association, but as a unique network structure whose flexibility and multilayered nature allow it to successfully adapt to new global trends. The main research focus of the work is on identifying the specific features of BRICS’s organizational ties as an association of states from the Global South and on analyzing the impact of its large-scale expansion in 2024-2025 on these ties. The authors demonstrate that, unlike formal international organizations with a rigid hierarchy (e.g., NATO) and even other club formats (G7, G20), BRICS builds interactions based on the principle of a complex network. This network encompasses not only the intergovernmental level (summits and ministerial meetings), but also a diversified grassroots infrastructure: over a hundred working groups, business and expert councils, university networks, and a rapidly developing partnership between cities and municipalities. This density of the network, according to the authors, ensures the stability of the association even during periods of weakening political coordination at the highest level. The article devotes particular attention to the dual nature of BRICS expansion. On the one hand, the transformation of the “old five” into the “big ten” (with the addition of Egypt, Iran, the UAE, Ethiopia, and Indonesia) enhances the global legitimacy, representativeness, and economic weight of the association, strengthening its position as a center of a multicentric world. On the other hand, the authors identify a range of internal challenges associated with the increasing complexity of network structures: more cumbersome and slower decision-making, competition for leadership between “old” and “new” members, the expansion and potential overload of the agenda with national and regional priorities, and the risk of new nodes and interest groups forming within the network. The article contributes to the study of the transformation of global political organization and offers a framework for understanding the role of informal network structures in contemporary world politics.