Energy is essential for development. No developing society can hope to achieve economic sustainability without adequate energy supplies. Virtually every aspect of economic and social activity demands energy. The unavailability of modern forms of energy to some two billion of the world’s population, and inadequate supplies to an estimated additional two billion people, is a major challenge to the achievement of the poverty, gender and health objectives of the United Nations Millennium Development Goals and the Plan of Implementation of the World Summit on Sustainable Development. At the same time, energy generation using fossil fuels is the principal source of greenhouse gas emissions that cause global warming. The mining and processing of fossil fuels can also endanger the lives of miners, cause severe land disruption and pollute land, air and waters. Furthermore, burning fossil fuels emits nitrogen and sulphuric oxides that are themselves toxic and are the precursors of urban smog and acid rain, while coal-burning power stations are responsible for mercury emissions that bio-accumulate in ecosystems, presenting a threat to human health as well as the environment. Providing the energy essential for development while minimising environmental hazards is one of the principal challenges in the 21st century.Energy efficiency offers perhaps the greatest potential to greatly reduce the amount of polluting energy needed to achieve current and future development targets. By eliminating waste, efficiency can often be accomplished at a profit or with a very short payback period of a year or two. Renewable energy, in the form of energy produced from solar, wind, sustainably managed hydro, geothermal and biomass resources, offers the potential to significantly displace the need for polluting fuels. These renewable resources are emphasised in the Plan of Implementation of the World Summit on Sustainable Development. This chapter therefore contends that, while much has been written about the science, technology and policies for promoting energy efficiency and renewable energy, little has been written about the legislative and regulatory options necessary to implement these technologies and policies that make a reality in practice. By promoting clean and efficient energy use at the legislative and regulatory levels, governments can ensure that all stakeholders have the opportunity and incentives to adopt new practices that will help to mitigate climate change and reduce pollution while keeping on the path of economic and social development. It is against this background that this chapter seeks to realise the following objectives: 1) To underscore the importance of efficient and renewable energy to produce electricity for the mitigation of climate change and sustainable development in Nigeria; 2) To provide an overview of the policy, legislative and regulatory measures available to promote energy efficiency and renewable energy as well as climate; change mitigation and adaptation in Nigeria; 3) To highlight the challenges and strategies to overcome the barriers to use and regulation of renewable and efficient energy for electricity in Nigeria.