This study evaluates the nexus of regional integration, socioeconomic determinants and sustainable development (SD) by investigating the effect of health, humans and age structure on sustainable development, with the regional integration (RI) as the moderating variable. Socioeconomic determinants have an important role in sustainable development, while regional integration has fueled up the development process. The sample is based on 64 Belt and Road (BRI) countries from 2003–2018. Pair-wise correlation results indicate that human development, health expenditure and age structure showed a positive relationship with sustainable development. Two-step System-GMM direct effect outcomes are mixed and reveal that human development, health expenditure per capita, age structure, governance index and population size have a positive impact on sustainable development. On the other hand, e-government, government size, and globalization showed negative effects on SD. Apart from that, the moderating channel of regional integration (RI), interaction term with human development and health expenditure, showed a significant and positive impact on sustainable development. However, age structure interaction with regional integration showed a negative impact on SD. Other socio-economic factors, i.e., governance index and population contribute positively towards SD. It can be concluded that the dynamic nature of sustainable development is positive and the net present value is increasing. Therefore, BRI countries are on the sustainable path from 2003–2018, as suggested by economic and social welfare theory. The integration of BRI can be labeled as an entrance to successful sustainable development. However, weak e-government systems, globalization and government resources need to be utilized amicably in Belt and Road countries. Driscoll-Kraay standard-errors regression confirmed and validated the two-step System-GMM results. The findings of the current research have important policy implications for balanced and sustainable growth.