This study is a critical evaluation of the Impact of Electricity Power Supply on the Performance of Small and Medium Scale Enterprise in Nigeria. The researcher made use of Ordinary Least Square (OLS) regression technique in analysing the Impact of Electricity Power Supply on Small and Medium Scale Enterprise in Nigeria. There are also other variables that determine the performance of Small and Medium Scale Enterprise. Findings from the study shows that all the variables included in the model contributes in explaining the performance of Small and Medium Scale Enterprise in Nigeria which shows R2 0.8899. The contributions of these variables may strongly depend on the circumstances in Nigerian economic environment. The study found out that a unit change in Electricity Power Supply has a positive impact on the output of small and medium scale Enterprise. Based on the findings, certain recommendations were made which include government increasing investment in the power sector, government policies aimed at encouraging SMEs to access public equity capital and also a need for an opening of the market for greater competition in the supply and distribution of electricity.