This study investigates the effect of irregular migration on Nigeria’s security in the North-West, a region increasingly vulnerable to complex security challenges. Irregular migration, characterized by undocumented movement across porous borders, has become a critical concern as it intersects with local instability, weak border governance, and transnational criminal networks. The research problem centers on how irregular migration contributes to the escalation of security threats in Nigeria’s North-West, an area already burdened by armed banditry, communal clashes, and socio-political tensions. Drawing on qualitative analysis of policy documents and security reports, the study explores the political, social, and security dimensions of this phenomenon. Findings reveal that politically, irregular migration undermines the legitimacy of state institutions by exposing their inability to control borders and manage demographic pressures effectively. Socially, it intensifies competition over scarce resources, deepens communal divisions, and contributes to rising xenophobic sentiments against perceived “foreign” settlers. From a security perspective, irregular migration creates opportunities for armed groups and criminal networks to recruit fighters, smuggle weapons, and establish cross-border safe havens, thereby complicating counterinsurgency and anti-banditry efforts. The study concludes that irregular migration significantly amplifies existing vulnerabilities in Nigeria’s North-West, requiring comprehensive and coordinated policy responses. It recommends strengthening border management through technological surveillance and community-based reporting systems, enhancing regional cooperation with neighbouring countries, and addressing the socio-economic drivers that compel irregular movement. By adopting a multidimensional approach, Nigeria can mitigate the destabilizing impacts of irregular migration and enhance human security in the North-West region.