A major challenge facing Nigerian government in the recent times is menace of insecurity. Nigeria as a giant nation in Africa is filled with chaos, anarchy and disorderliness and violent conflicts. These backgrounds bring about natural desire to go into this research work. The study investigates the effects of insecurity on the economic growth of Nigeria economy between 2000 and 2020. Data on Real Gross Domestic Product (RGDP), Government effectiveness, inflation rate and unemployment rate were sourced from the Central Bank of Nigeria Statistical Bulletin (2020) while data on Terrorism were sourced from Global Terrorism index. Data collected were analyzed using tables, graphs, Autoregressive Distributed Lag model method (ARDL).Findings from the study reveals that the effect of terrorism risk index on the real GDP is negative and significant. This implies that insecurity not only disrupts economic activities but also has negative impact on the real GDP of the economy as speculated by various economic theories. Also, the study finds that government effectiveness affects real GDP positively.  This implies that Government effectiveness in Nigeria has positive impact on Real Gross Domestic Products (RGDP) in Nigeria. Also unemployment has negative effect of the level of economic growth in Nigeria. The study therefore recommends that government should take the business of governance seriously and redress issues of injustices, victimization, marginalization, discrimination, security and also create a safe and an enabling environment for investments which will step up industrialization and sustainable development thereby enhancing the livelihoods of the greatest numbers of its citizens.