Studies and institutional reports have argued that youth violence is a precursor to national insecurity in Nigeria. Contrary to youth as an agent of transformation and national development, their recurrence in violent conflicts has continued to undermine the national security of the country. Such security backlash is further conflated by the protracted Boko Haram insurgency which has ruptured the nation building, but also tugs on the sovereignty of the Nigerian state. While these phenomena have increasing implication for the country stability; youth violence across various communities in Lagos State, a megacity; the economic nerve centre of the country has further put Nigeria’s economic prosperity and security architecture in dire strait. This security deficit is the prevalence of anomie and lawlessness in Ikorodu Local Government area of Lagos State, instigated by the crisis of urbanisation, land grabbing, demographic pressure and cultism. This study examines youth violence and the failure of the Nigerian state, with focus on Onyabo Vigilante Groups (OVG), as a crucial actor in curtailing violence in Ikorodu Local Government of Lagos State. Using a qualitative method as a frame of analysis, the study argues that the lack of state capacity, resulting in unemployment, abject poverty and poor socio-condition is responsible for the widespread incidences of youth violence instigated by land grabbing and cultism in Ikorodu Local Government. The study concludes on the imperative of overhauling the security architecture of the state, to recognise vigilante groups legally and institutionally, as a complementary security outfit to the Nigerian police. More importantly, questions of poverty, unemployment and social dislocation should be put on the front burner of government developmental agenda to forestall hopelessness and frustration which are frequent condition breeding violence in Nigeria. Key words: State, vigilante, youth violence, Onyabo, Ikorodu.