The researcher as a sine qua non in the economy viewed Effects of Power Supply on the performance of Small and Medium Scale Enterprises. However, firms suffer tremendous cost due to serious supply deficit of electricity in Nigeria, which greatly hampers businesses, especially the small-scale enterprise. The researcher used both primary and secondary methods of data collection, presented the data in tables using simple percentages and chi-square to analyze the data obtained. The findings of the research among others were that there are possible ways of improving power supply in Nigeria through facilitating in both private and public investment in electricity infrastructure by the Government, epileptic power supply hinders profitability of the business, adequate power supply enhances profitability in business and there is significant relationship between power supply and SMEs performance in Nigeria. The researcher recommended that Intensive funding of researches into alternative sources of energy e.g. solar and wind, should be pursued immediately and that Government should also pursue its current privatization policy of the distribution of electricity in Nigeria transparently ensuring that the approval investors are reputable technocrats in power operations.