Since circular economy (CE) and green transition (GT) concepts emerged at the Earth Summit in 1992, they have become increasingly popular in environmental economics sectors with great attention. Currently, our world has provided a limited flow of resources due to the disproportionate use of non-renewable resources over the past decades. Recent studies have found that the concepts of CE and GT have been used in developed nations to overcome resource-related challenges. These concepts are applied in sustainability sectors by addressing scientific findings, trade and policy. Moreover, these concepts promote socio-economic development and ecological goals for improving human-nature interaction and enhancing global net sustainability. Hence, these concepts act as a complete package of solutions in the context of the environment and economy. Although CE and GT provide valuable support for sustainable development and environmental conservation, these concepts are yet to be widely promoted in developing nations. In these circumstances, introducing these concepts into regional and national policy frameworks is necessary. Furthermore, the effectiveness of these concepts in sustainable development-related scientific investigations should be explored to establish them in developing nations. Hence, this chapter aims to discuss CE and GT from both public and private decision-making perspectives. Moreover, as the implementation of CE and GT is crucial to developing a sustainable environment and future, this chapter investigates the political, economic and social challenges of promoting and implementing these concepts at the national and regional levels. Lastly, this chapter aims to support policymakers implementing these concepts in developing nations.