Waste is an indispensable by-product of most human daily activity. Prevailing waste management strategy, especially in developing countries such as Nigeria, is far below standard, resulting in environmental contamination and pollution which hampers sustainability. This forms the crux of the research paper which entails ascertaining how Waste-to-Energy can serve as a circular economy tool towards climate mitigation that will ensure environmental sustainability. Key challenges relate to moving beyond the perception of ‘waste as a problem’ to ‘waste as a resource’. Ultimately, both waste prevention, as well as a widespread growth in circular economy activities, will require a coherent and holistic approach that takes recovery options into account at every stage of the product life cycle. To achieve this, the study explored the potentials inherent in Waste-to-Energy (WtE) as a tool. The work is qualitative and involves a synchronic evaluation of previous research works relevant to the study to ascertain the viability of WtE as a circular economic tool for scaling back adverse environmental impact. Integration of results with detailed clarifications of circular economy and climate mitigation indicates WtE as an index of sustainable development. The bottom ash from combustion operations serves as feedstock to the construction industry, hence closing a potential pollution loop. Therefore, Waste-to-Energy is ascertained a viable tool that supports the circular economy while coupling with progressive externalities of climate mitigation. Thus, the study recommends that WtE as a tool should be duly considered as a key feature of climate change policy in developing countries, especially in Nigeria.