<p>Environmental sustainability remains a critical global challenge, with the world’s major carbon polluters contributing disproportionately to environmental degradation and climate change. Through its Sustainable Development Goals and 2030 Agenda for Sustainable Development, the United Nations calls for all countries to collaborate their efforts to ensure sustainable development. Despite substantial international initiatives toward enhancing environmental quality, there is an urgent need for more targeted action. This study examines the roles of financial technology (FinTech), human development, economic growth, and fossil fuel energy consumption in environmental sustainability in the world’s top carbon-emitting countries from 2013 to 2019 by employing the Method of Moments Quantile Regression (MMQR) and Feasible Generalized Least Squares (FGLS) estimation techniques. The MMQR model results show that economic growth (coefficients: 0.08–0.17), fossil fuel energy consumption (coefficients: 0.23–0.26), and financial technology (coefficients: 0.23–0.56) increase carbon dioxide (CO₂) emissions, while human development (coefficients: -5.69 to -12.70) decreases them, across all quantiles of the CO₂ distribution. The magnitudes of the effects of economic growth and financial technology on CO₂ emissions decrease with increasing quantiles (from 5 to 95th quantile), while those of fossil fuel energy consumption and human development increase with quantiles. The FGLS model results validate the robustness of the MMRQ model results. Given these findings, policymakers should implement differentiated carbon pricing mechanisms<b>,</b> establish quantile-based renewable energy quotas<b>,</b> promote human development through education and healthcare, and foster green FinTech practices and innovation.</p> Graphical abstract <p></p>