This study explores the role of digital humanities (DH) and urban digital heritage (UDH) in advancing urban circular economy (UCE) across 18 countries, focusing on three core UCE pillars: resource reuse, low-carbon transition, and circular governance. By analyzing 48 DH projects implemented between 2021–2025, the research identifies five synergistic mechanisms through which UDH enables circularity: cultural heritage-driven resource optimization, digital documentation of traditional circular practices, participatory circular governance via UDH platforms, low-carbon preservation technologies, and circular economy (CE) value creation through heritage digitization. Findings reveal that context-adaptive DH initiatives integrate cultural preservation with resource efficiency, though effectiveness is mediated by policy integration (e.g., national CE strategies), technological adaptability, and cross-sector collaboration. The paper proposes a UDH-UCE Integration Framework to guide inclusive, culturally sensitive circular urban development.