The requirements for children’s health, well-being, and education are covered in Sustainable Development Goals 3 and 4. In response to the crisis in survival and development sustainability faced by children during the COVID-19 pandemic, China adopted the temporary guardianship system. The purpose of this study is to examine whether this system does contribute to safeguarding children’s sustainable development, well-being, and health. The study adopted a descriptive qualitative approach with content analysis and applied qualitative document analysis of relevant regulations. Data were obtained through 12 semi-structured, in-depth interviews with the institutional staff and individuals. The results indicate that the multiple supports provided to children during the COVID-19 pandemic by the institutions and individuals responsible for assuming temporary guardianship were basically adequate to meet the needs for achieving children’s objective well-being and sustainable development and safeguarding their health. Despite some deficiencies, the temporary guardianship system is worthy of becoming a sustainable system for supporting children’s sustainable personal development and safeguarding their health and well-being, and of serving as a blueprint for other countries to pursue Sustainable Development Goals in times of sudden public emergencies.