This study examines Nigeria’s slow progress toward universal healthcare coverage (UHC), analyzing the policy development process and the roles of various actors involved. Using social network analysis (SNA) and qualitative methods, we conducted structured interviews and documentary analysis to identify key policy actors and their relationships within the UHC network. The SNA revealed a complex structural network categorizing actors into four groups: power actors, peripheral actors, gatekeepers (brokers), and isolated actors. These classifications determined their access to information, professional support, and resources. A stable subset of seven organizations demonstrated significant centrality and influence across multiple relationships, while other organizations were central only in specific contexts. Senior government officials emerged as the primary influencers in UHC policy development and decision-making, controlling information flow within the policy network. These actors played crucial roles in advancing and impeding UHC progress in Nigeria. The study identifies political, policy-oriented, financial, and organizational constraints as significant barriers to UHC implementation. Addressing these challenges is essential for improving financial protection and ensuring Nigerians have equitable access to essential healthcare services. Our findings contribute to understanding the complex interplay of actors in healthcare policy development in low- and middle-income countries, offering insights that could help accelerate progress toward achieving UHC in Nigeria and similar settings.