Climate change and global warming have become major challenges to sustainable development, increasing the importance of understanding the economic and financial determinants of environmental quality. This study investigates the long-run effects of economic development and financial development on environmental quality in selected countries using panel data covering the period 1973–2024. Inresource-rich economies, oil revenues can serve as an important source of financing for financial sector development and technological advancement. When these revenues are strategically allocated to promote innovation and cleaner production technologies, they can significantly reduce carbon emissions and improve environmental quality. Conversely, directing such resources toward pollution-intensive industries without adequate environmental considerations may result in severe and irreversible environmental degradation. Therefore, financial development constitutes a key determinant of environmental performance and should be explicitly incorporated into environmental policy analysis. The empirical findings reveal that financial development has a statistically significant negative effect on carbon dioxide (CO₂) emissions, indicating its contribution to environmental improvement. Furthermore, the relationship between economic development and greenhouse gas emissions is found to be nonlinear, following a quadratic functional form consistent with the Environmental Kuznets Curve (EKC) hypothesis. These findings suggest that strengthening the financial sector, together with channeling financial resources toward environmentally sustainable investments and technological innovation, can play a crucial role in improving environmental quality and promoting sustainable economic development in the selected countries.