Urban farming has expanded across Nigerian cities in response to rapid urbanization, food insecurity, unemployment, and ecological stress. Yet, existing analyses often treat it as an isolated livelihood strategy or a narrow food security intervention. This narrow framing creates an important analytical challenge because it obscures the governance relations, infrastructural conditions, and ecological processes through which urban farming is produced, constrained, and sustained. This paper develops a conceptual framework for understanding urban farming in Nigeria as a socio-ecological component of urban food systems. Building on a critical review approach adapted from recent social-ecological urban food systems scholarship, the paper integrates governance dynamics, networked resource flows, urban infrastructure and spatial form, and social-ecological dynamics into a unified analytical model. Drawing on foundational food systems thinking and urban social-ecological systems literature, the framework positions urban farming as embedded in power relations, material and metabolic flows, infrastructural configurations, and ecological processes. The paper contributes to the literature by synthesizing socio-economic and ecological perspectives into a layered analytical framework tailored to Nigerian cities, identifying conceptual gaps in current scholarship, and highlighting practical implications for research, planning, and policy. It therefore moves the discussion beyond descriptive livelihood accounts toward a more systemic understanding of how urban farming can contribute to sustainable and resilient urban food systems in Nigeria.