This study investigates the impact of income distribution as poverty reduction on sustainable development (SD), by taking the moderating role multidimensional regional integration (MRII) in fostering the integrated sustainability across 64 Belt and Road Initiative (BRI) countries from 2005 to 2020. Utilising Sys-GMM methodology, the findings support the notion that countries within the BRI are theoretically aligned with a sustainable development path as suggested by economic theory. Moreover, MRII significantly contributes to the integrated sustainability path. The direct channel analysis reveals a negative yet significant effect of income distribution on sustainable development, indicating an increase in disparity and capital management system. Conversely, the indirect channel suggests a reduction in disparity and regionally integrated BRI boost the sustainable poverty reduction. This study identifies positive contributions from macroeconomic conditions, institutional quality, and population size to BRI countries' sustainable development. Additionally, it suggests the inefficient utilisation of resources by BRI countries, particularly in government consumption. The study underscores the need for enhanced regional policies aimed at increasing income and reducing poverty to foster sustainable development. Upcoming research should investigate the unexplored effects of household consumption, financial inclusion, financial aid, and energy poverty influence on integrated sustainability, regarding global financial integration.