Movement of people across the international boundaries is a universal phenomenon, which can be legal or illegal depending on the circumstances warranting them. On 28 May 1975, a treaty establishing ECOWAS was signed by West African States to promote co-operation in economic activity for closer relations among its members. The Protocol on Free Movement of Persons, Goods and Capital and the Rights of Residence and Establishment was enacted in 1979 to ensure the abolition of obstacles to free movement of persons, services and capital. The study investigated how the implementation of the Protocol within the Seme border between Nigeria and Benin Republic have impacted on human security with emphasis on the influx of SALW into Nigeria. The study aims at achieving two specific objectives, viz: to determine whether the implementation of the ECOWAS protocol account for the escalation of crimes in Nigeria and Benin between 1999 and 2016; and to ascertain whether the ECOWAS Free Movement Protocol of persons enhance threat to human security within the border area between Nigeria and Benin Republic between 1999 and 2016. The study employed time series design; data was sourced through secondary sources and qualitative descriptive method of analysis was used to analyze the data generated. Anchoring our analysis on the Post-Colonial State, the study revealed that the proliferation of small arms and light weapons poses serious challenges to Human Security, especially in Nigeria through the influx of SALW. The study therefore recommends that the ECOWAS protocol should be properly readjusted, redesigned and properly implemented to prevent the escalation of crimes between both countries.