An illicit market is a system which involves the buying and selling of goods and services which a society classified as inimical to its existence. This study utilized the rational choice theory in explaining the phenomenon of illicit market and transnational organized crime in West Africa. Explanatory research method was utilized in explaining the pattern and trend of the phenomenon. The activities of these criminals in illicit market and organized crime are found in the US, Canada, Europe and Africa. Recently, West Africa has become the hub of global illicit market with countries like Guinea, Liberia and Nigeria as major transit pot of hard drugs and other illicit goods from South America.