Abstract: National sovereignty, as the fundamental guarantee of a country’s independent development, embodies both the internal capacity to exercise supreme authority and the external right to enjoy equal status among nations. It serves as an indispensable cornerstone for safeguarding national security, institutional stability, and the integrity of the governance system. Social governance, on the other hand, fulfills critical functions such as maintaining social order, delivering public services, and promoting fairness and justice, acting as a key pillar in advancing the modernization of a nation’s governance capabilities. However, the rapid emergence of the Cyber–physical–social–thinking (CPST) space—an interconnected hyperspace blending cyber, physical, social, and thinking spaces—has fundamentally altered the landscape in which both sovereignty and governance operate. This new environment presents unprecedented challenges that demand a reimagined framework to sustain national authority and public welfare. In the context of the CPST, national sovereignty is facing severe and unforeseen threats. Traditional geographic boundaries are becoming increasingly blurred, complicating the enforcement of jurisdictional authorities. State and non-state actors can launch cyberattacks that target critical infrastructures, orchestrate disinformation campaigns, and engage in ideological infiltration, all of which erode the nation’s control and legitimacy. Simultaneously, traditional hierarchical models of social governance have proven inadequate, often suffering from slow response times to rapidly evolving crises, insufficient coordination among agencies, and limited mechanisms for meaningful public participation, leading to gaps in service delivery and policy effectiveness. To address these challenges, this study proposes a framework for national sovereignty and social governance based on CPST space theory, systematically analyzing the collaborative logic between national sovereignty and social governance. On the one hand, national sovereignty is evolving and extending across multiple dimensions within the CPST space. It is no longer confined to territorial land, sea, and air but now encompasses digital territories, data flows, and cognitive spheres. New forms of sovereignty, particularly data sovereignty—control over a nation’s data generation, storage, transfer, and utilization—are emerging as defining elements of contemporary power. On the other hand, social governance is undergoing a parallel transformation, transitioning toward an intelligent model best described as a “data perception-intelligent modeling-efficient decision-making”. This model leverages the vast amount of data generated in the CPST space to achieve unprecedented precision and efficiency. Governance systems can perceive societal dynamics in real time through ubiquitous sensors, IoT devices, and social platforms. Artificial intelligence and big data analytics then process this information to model complex social trends, predict risks, and simulate policy outcomes. Finally, these data-driven insights enable the authorities to make efficient evidence-based decisions, dynamically allocate resources, and move from reactive problem-solving to proactive governance. It takes Hangzhou’s “urban brain” as an example to explore the feasibility of the transformation of social governance towards precision and proactivity. In conclusion, the integration of national sovereignty and social governance within the CPST framework is not merely an academic exercise but a practical necessity. By understanding the synergistic evolution of sovereignty and harnessing intelligent governance models, nations can navigate through the complexities of the digital age. This provides the requisite support for developing resilient national sovereignty and reforming social governance paradigms, ultimately ensuring stability, security, and prosperity in an increasingly interconnected world.