The implementation of a circular economy (CE) in the construction sector faces several challenges that hinder its progress. Research on the awareness, key enablers, and potential benefits of CE in Saudi Arabia’s construction of mega-projects that could contribute and promote a successful transition is still at its early stages and remains limited. This study delves into CE awareness and understanding, identifying the key enablers that could support its successful adoption in Saudi Arabian mega-projects and the potential benefits associated with it. To achieve this, a comprehensive literature review was conducted, followed by 18 semi-structured interviews across three case studies, which involved the main stakeholders in building, urban development, and infrastructure projects. The findings, which are thematically analysed, revealed that CE awareness mostly focuses on reuse, recycle, and waste reduction. A significant gap in the knowledge of circularity throughout projects’ lifecycles has been identified. As such, this study concludes that the key enablers for CE include establishing regulatory frameworks, enhancing professionals’ awareness and education, promoting the use of advanced technology, ensuring a mature market, and supporting CE initiatives. Moreover, the potential environmental and socio-economic benefits of CE, such as cost reduction, environmental impact reduction, and better-improved quality of life are crucial for encouraging a wider implementation of CE in the construction of mega-projects in Saudi Arabia.