Climate change remains one of the most pressing global challenges, highlighting the urgency of identifying the key drivers of environmental sustainability. Although the G-7 economies (Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States) play a pivotal role in shaping the global climate agenda, empirical evidence on the determinants of their environmental sustainability remains relatively limited. This empirical study seeks to bridge this gap by estimating the heterogeneous effects of economic growth, renewable energy consumption, non-renewable energy consumption, technological innovation, industrialization, human capital development, and stringent environmental policies on environmental sustainability in G-7 countries using panel data over the period 1993-2023. Employing the Method of Moments Quantile Regression (MMQR) methodology, the empirical analysis captures the differential impacts of these factors across varying levels of sustainability performance. The empirical results reveal that economic growth, non-renewable energy consumption, technological innovation, industrialization, and stringent environmental policies tend to deteriorate environmental sustainability, whereas renewable energy use and human capital development enhance it. The findings highlight the urgent need to reorient technological innovation toward resource efficiency, accelerate the transition to renewable energy sources, and increase investment in green innovation and advanced nuclear technologies. Additionally, the study emphasizes strengthening green finance and restructuring fossil-fuel-dependent industries to align G-7 economies with global climate commitments and long-term sustainability goals.