The concepts of circular economy (CE) and sustainability (S) have lately gained momentum among scholars, theorists, academics, and practitioners. Although these concepts are considered necessary to solve many of the existing global environmental and social challenges (e.g., climate change, nature conservation and social equity), it seems there is no consistency relating to their content. Some scholars consider these two concepts identical, while others contemplate them as different. Several theoretical approaches have been presented to clarify the content of these two concepts and to provide effective ways to solve the social and environmental problems. The goal of this paper is to examine the existing literature regarding the content of CE and S based on a triple-level analysis (micro, meso, and macro level) across different scientific fields: economic/management and engineering/natural science. Our findings show many theoretical approaches with several relationships, similarities, and differences among CE and S at the micro, meso, and macro-levels within engineering and management scientific fields. Based on these findings, a future research agenda on CE and S is also proposed. Keywords Circular business model . Sustainable business model . Corporate Social Responsibility and circular economy . Circular corporate accounting . Corporate reporting and circular economy . Environmental engineering and firms . Wastewater and circular economy . Reuse and firms . Recycle and firms . Industrial ecology and circular economy . Industrial symbiosis and circular economy . Industrial metabolism . Eco-clusters and circular economy . Eco-industrial park . Circular economy and 17 SDGs