Circular architectural design reimagines built environments by embedding regenerative resource flows into early design decisions. This chapter investigates how artificial intelligence can transform early-phase architectural design (RIBA Stages 0–2), where decisions most impact circularity. Moving beyond AI as merely a performance optimiser, we position it as a futuring tool enhancing strategic definition and concept design through Tony Fry’s design futuring framework. We demonstrate that when guided by principles of design intelligence, redirective practice, temporal awareness, and ethical design, AI becomes a catalyst for “sustain-able” transformation. The chapter presents applications showing how AI reveals hidden material flows, generates reuse-based alternatives, provides real-time feedback, and visualizes adaptation scenarios. Through examples, we discuss how AI augments creativity while embedding circular principles at the core of spatial projects. We explore how AI-driven circular design advances sustainability objectives, linking circularity to broader environmental goals while balancing technical optimization with social equity. In conclusion, this research advances design discourse by elucidating how AI can transform early phases of circular architectural design. The five identified directions are: extending human perception to reveal patterns in complex datasets and translate them into actionable intelligence; expanding solution spaces with sustainable alternatives that position circularity as the logical choice; embedding long-term foresight into design decisions via sophisticated predictive modeling; foregrounding ethical considerations through transparent sustainability metrics; and enhancing creative potential through collaborative human-AI partnerships that transcend individual expertise boundaries.