Circular economy (CE) is hinged upon resource optimisation as a more viable and sustainable approach against the extractivist linear economic model that has resulted in resource scarcity, affordability issues, and environmental degradation. Design plays a critical role as the foundation of the circular approach, however, limited studies have examined the inherent benefits of circular design (CD) adoption from the building design firms’ (BDFs) perspectives, more importantly, none exist in Nigeria to the best of the author’s knowledge. This study assesses the benefits of CD adoption in the Nigerian building industry (NBI). Primary data were collected from 216 architectural and engineering design firms domiciled in Lagos using a questionnaire survey. The findings indicated the top five benefits which include reduction in energy use by efficient utilization through design, development of new skill sets in circularity by design teams, reduction in pollution through reduced burning of fossil fuel, reduction of construction/demolition waste generation, improvement of public health by preserving local biodiversity. While increasing competitiveness amongst BDFs and resource security through optimisation and dematerialisation were ranked the least. The outcome can be ascribed to the fact that Nigeria currently faces an energy crisis with efforts being made in developing energy-efficient buildings and the need to minimize the environmental impact of construction practices. It was suggested that BDFs need to invest in CD expertise development through training and education, voluntary stewardship, and providing the requisite technologies to aid CD implementation. This study provided the basis for the needed debates on the relative benefits of CD adoption in the NBI.