iarjhssIARJHSSIARJHSS2708-6267https://doi.org/10.47310/iarjhss.2021.v02i01.005Illegal Cross-Border Engagements and Undocumented Migration: Obstacles to Border Security in Nigeria And West African Sub-RegionTemitopeFrancisAbiodunMarcusTemitayoAkinladeDepartment of Peace, Security and Humanitarian Studies, Faculty of Multidisciplinary Studies, University of Ibadan, Ibadan, NigeriaDepartment of Political Science and International Diplomacy, School of Social and Management Sciences, Bamidele Olumilua University of Education, Science and Technology, Ikere-Ekiti, NigeriaThe research is mainly focused on incidence of illegal cross-border activities and engagement of people in undocumented migration that has taken a toll on the Nigerian and other African states’ borders and this has posed numerous obstacles to border security and management in the state and the continent at large. The study adopts the theory of migration systems to shed lights on the synergy between migration/information, and subsequent exodus of people. Towards attaining its objectives, the study employed the use of quantitative and qualitative research methods with significant reliability index. Towards attaining its objectives, the major factors giving way to the illegal cross-border engagements and undocumented migration along Nigerian borders are examined and identified by the study to include: absence of good governance, corruption, incessant conflicts in Africa, porous border, poverty, and growing illicit trade among others. The study also finds out the threats posed by the menace on the state and Africa at large, as the Nigerian borders with; Cameroon, Chad, Niger and Benin Republic are highly porous, thereby aiding proliferation of arms and weapons and has inflicted more injuries to national security and economy of Nigeria. The study in the long run, recommends among others that; there should be cross-fertilization of security ideas and transnational synergy between Nigeria and her neighbouring states to fight illicit activities at borders while the institutions saddled with migration and population control and identity management in Nigeria should wake to re-jig themselves.