<p>The Belt and Road Initiative (BRI) presents both opportunities and challenges for environmental sustainability. In BRI countries, the impact of population changes, economic growth, and technological advances on the ecological environment is becoming more pronounced. To investigate the heterogeneous impacts of population aging, birth rate, economic growth, energy decarbonization, and information and communication technology (ICT) on environmental sustainability in BRI countries, this study employs quantile regression and analyzes data across 120 BRI countries, considering the non-additive fixed effects under the STIRPAT framework. Ecological footprint (EF) and biocapacity (BC) are selected as indicators of environmental pressure and capacity, respectively. The findings reveal that: (1) While population aging significantly enhances BC, its impact on EF transitions from negative to positive and intensifies with increasing EF quantiles. (2) Although energy decarbonization contributes to reducing EF, it also diminishes BC. At higher BC quantiles, the adverse impact of energy decarbonization on BC substantially outweighs its mitigating effect on EF. (3) Across nearly all quantiles, the negative impact of ICT on BC is more pronounced than its mitigating effect on EF. (4) At higher BC quantiles, the EF induced by economic growth exceeds the enhancement in BC. Based on these findings, BRI countries at higher EF quantiles must prioritize addressing the environmental pressures stemming from population aging. Furthermore, BRI countries at higher BC quantiles ought to strategically manage the environmental challenges posed by economic growth, energy decarbonization, and ICT development to advance environmental sustainability.</p> Graphical abstract <p></p>