Nigeria entered the third decade of the twenty-first century carrying one of the largest absolute populations of poor people in the world, with the National Bureau of Statistics reporting that 133 million people—roughly 63% of the population—are multidimensionally poor. This paper offers a policy and institutional analysis of the country’s national social protection and poverty reduction architecture, tracing its evolution from fragmented, donor-driven safety nets toward the codified ambitions of the 2017 National Social Protection Policy and its 2021 revision. Using the four-function (protective, preventive, promotive, and transformative) framework of Devereux and Sabates-Wheeler (2004) as an analytical lens, the study maps the three principal pillars of provision: non-contributory social assistance delivered through the National Social Investment Programme and the World Bank-financed National Social Safety Nets Project; contributory social insurance organised around the Pension Reform Act 2014 and the National Health Insurance Authority Act 2022; and labour-market interventions. The analysis finds that Nigeria has built impressive technical infrastructure—most notably a National Social Register covering more than 70 million individuals—yet remains hampered by chronic coverage gaps in the informal economy, fiscal under-investment, institutional fragmentation and overlap, weak legal entitlement, and recurrent governance failures, exemplified by the 2024 suspension of the National Social Investment Programme Agency amid allegations of large-scale financial misappropriation. The paper concludes that durable poverty reduction requires moving social protection from a discretionary, project-based posture to a rights-based, adequately financed and institutionally coherent system, and offers concrete recommendations toward that end.