This systematic review critically examines the intersection of digital transformation and circular economy (CE) principles within the built environment. While digitalisation has been shown to enhance efficiency, safety, and sustainability in construction, its role in fostering circularity is less established. This study analyzes literature from 2010 to 2022, focusing on how digital technologies such as open-BIM, digital twins, material passports, blockchain, RFID, and gamification can integrate into and enhance the circular building lifecycle. The findings reveal that while digital tools are pivotal in design and construction phases, their application to existing structures is less straightforward, with challenges including the absence of digital twins for demolished structures, the high costs of retrofit digitalisation, and the predominant focus on environmental benefits over practical implementation. The review also highlights the need for a unified digital transformation strategy and greater cross-industry collaboration. Future research directions are proposed, including the development of localized material banks, the application of RFID in circularity, the scope of Design for Disassembly (DfD) tools, digital inventory of existing buildings, the circularity of Life Cycle Assessment (LCA) databases, and policy implications for promoting circular construction practices.