Abstract: The institutionalization of interim regulatory alignment mechanisms from the 15th National Games of the People’s Republic China (“the 15th National Games”) into sustainable regional governance frameworks constitutes a pivotal strategy for leveraging athletic cooperation to architect a new paradigm of high-quality development. Through logical reasoning and case analysis grounded in institutional coupling theory, this study establishes a three-dimensional analytical framework encompassing synergistic effects, learning effects, and systemic embeddedness mechanisms. It theoretically examines three provisional institutional innovations: the establishment of customs facilitation and coordination mechanisms, the unified yet flexible market development framework, and soft law coordination for dispute resolution. The findings indicate that synergistic effects manifest in the perceptible benefits derived from enhanced customs efficiency; learning effects are reflected in communication mechanisms such as the “1＋4” liaison system and bimonthly meetings, which evolve into cross-regional shared operational protocols and extend to non-sporting-event contexts; systemic embeddedness is demonstrated through anti-counterfeiting infrastructure reserving data interfaces for Hong Kong and Macao, as well as the integration of customs standards and cross-border dispute resolution collaboration into regional development processes. When incremental benefits outweigh the costs of reverting to previous institutional frameworks, and shared knowledge disseminates into non-sporting-event domains and is absorbed into higher-level governance documents, “embedded coupling” gains the foundation to transition toward “complementary coupling”. This study provides theoretical insights for constructing a self-sustaining regional sports governance ecosystem in the Guangdong-Hong Kong-Macao Greater Bay Area.