The findings from this work show that no single energy resource can sustainably meet the energy demands of Onitsha as the business hub of Anambra State. Integrating all exploitable energy sources is a viable way of achieving stability in energy supply for Onitsha, Anambra State Nigeria. Hence, the paper focuses on the role of energy mix in sustainable development of Onitsha the commercial hub of Anambra State, Nigeria and as it affects the environment. The impact of existing energy mix; crude oil, coal, electricity and renewable Energy on sustainable development of Onitsha is considered in this work. A sample of 375 respondents was randomly chosen in the study area based on the population. Questionnaire was designed and administered to inhabitants of the study area to enable the researchers ascertain information on the effect of energy mix on the economy and the environment and possible remedies. The Pearson’s product moment analysis correlation and Chi-square test were applied in the hypothesis testing. The result shows that huge amount of effluents are discharged on the environment in using fossil energy products thereby polluting the environment. This leads to radiative forcing which causes global warming. Also, the energy mix has not significantly influenced sustainable development given that electricity generation is inadequate and coal is no longer in use. To ensure proper recovery, the study recommends that government makes available alternative energy sources through subsidy re-investment in addition to the conventional power to save the environment; with this, waste becomes wealth towards a sustainable economy in Onitsha.