Child protection is a sensitive aspect of the social welfare systems across the globe as more children get exposed to abuse, neglect, trafficking, exploitation and other vulnerable factors that threaten their growth and well-being. This paper analyzes child protection and welfare systems in Nigeria with special reference to the application of social-work intervention. Using policy reports, legislative frameworks, government reports and academic literature, the paper discusses the institutional frameworks, legal provisions that influences child-protection mechanisms in Nigeria. The analysis is based on three issues: child-protection policies and law that govern child-welfare in Nigeria; the functions and roles of social workers in the systems; gaps and challenges that impact the effectiveness of child-protection interventions. The study, which is based on the Systems Theory, conceptualizes child protection as a network of interrelating institutions, such as welfare agencies, legal systems, health care services, schools, and community systems, which act in unison to protect children against harm. The evidence shows that Nigeria has come up with a number of legislative and policy frameworks, such as the Child Rights Act that have been established to help prevent abuse, exploitation and neglect of children. The adoption of these frameworks, however, is inconsistent because of the poor institutional capacity, lack of sufficient funding and inter-agency co-ordination, as well as lack of professionalization of social-work practice. The discussion also establishes that social workers are very significant as direct service providers, advocates of protective services, and coordinators of these services by performing various functions like case management, family support, counselling, rehabilitation, and community-based interventions. This research recommends that Nigeria needs to enhance its child-protection system by strengthening legal enforcement, better professional capability of its social workers, better institutional coordination and community based support system to protect and provide comprehensive welfare to vulnerable children.