The study examines the sources of external shocks and investigates their transmission channels in Nigeria using the trade-weighted variables from the country’s five top trading partners. Based on the assumption of the small open economy model, the study adopts the New Keynesian Dynamic Stochastic General Equilibrium Model on quarterly data between 1981 and 2018 using the Bayesian estimation technique. Findings from the study reveal that external shocks have a temporary and short-lived effect on the Nigerian economy. In addition, the article shows that oil price, foreign output, and foreign inflation shock have positive impacts on output gap and inflation, while the impact of foreign interest rate shock on the output gap and inflation is negative and not significant. The study also reveals that external shocks collectively explain 86% and 39%of total fluctuations in the output gap and inflation, respectively. Lastly, the study finds that external shocks transmit to the Nigerian economy via different channels. The study, therefore, concludes that terms of trade and exchange rate channels are the dominant transmitters of external shocks in Nigeria. Based on the findings from the study, important policy implications are highlighted.