This study examined the indigenous Knowle- -dge ecosystem and socio-cultural learning structures in informal Islamic schools in Northern Nigeria. The objective of the study is to explore the Almajiri educational system within the context of educational marinalizat- -ion. The study adopted a concurrent triangu- -ulation mixed-methods research design conducted in the densely populated Almajiri states comprising Kano, Sokoto, Kaduna, Niger, and Borno. A sample of 400 respondents was selected, and a return rate of 307 (76.7%) instruments was achieved. The findings showed that the Almajiri system remains an important indigenous educational institution sustained through the practice of Qur‟anic recitation (277, 90%), memorization (265, 86%), and respect for elders (300, 98%). The study revealed that the system's educational aim has been weakened by poverty (Mean = 3.98) and parental neglect (Mean = 4.0). The triangulated findings further showed that the Almajiri system enjoys religious legitimacy and cultural acceptance, but the contemporary condition results in severe educational marginalization and childrights vulnerability. Government reform efforts were found to be inconsistent (Mean = 2.31). The study established that the Almajiri educational system should not be viewed solely as an educational issue but as a multidimensional challenge involving the preservation of indigenous knowledge and child protection. It therefore recommends culturally sensitive reforms that integrate Qur‟anic education with formal education and provide welfare support for Almajiri pupils