During the period January–June 2025, JSI, as the Zero-Dose Learning Hub (ZDLH) global learning partner, continued to provide technical assistance and collaborate closely with the Nigeria Learning Hub, led by the African Field Epidemiology Network and the Africa Health Budget Network. This semiannual update for the Gavi and other stakeholders highlights the Learning Hub’s efforts to leverage evidence for a deeper understanding of the factors that affect the implementation and performance of strategies to identify and reach zero-dose and under-immunized children and missed communities in Nigeria. Key efforts included expanded Decentralized Immunization Monitoring across four states, implementation research on the Zero-Dose Reduction Operational Plan, and continued capacity strengthening and data quality assessments to improve routine monitoring and planning. Findings showed modest but meaningful gains in DTP1 and DTP3 coverage and a decline in zero-dose prevalence, identified gender and social constraints as persistent barriers to uptake, and demonstrated how evidence-based advocacy helped drive substantial improvements in subnational immunization financing. This report synthesizes findings, challenges, and recommendations emerging across Gavi’s IRMMA framework.