<p>This study scrutinises the correlations between energy productivity, CO productivity, and economic structure across ASEAN countries. It utilizes data from the OECD and the World Bank (2005–2021) to explore how energy efficiency improvements correlate with CO₂ emissions reductions across the region’s economic sectors: agriculture, industry, and services. Based on multiple linear regression analysis, the results show a positive relationship between energy productivity and CO₂ productivity. This suggests improvements in energy efficiency can support environmental goals. Sectoral analysis indicates that agriculture demonstrates a significant positive correlation with CO₂ productivity; industry shows a marginally negative association; and services render no significant effect. The finding pinpoints that energy efficiency enhancement is vital in decoupling economic growth from environmental degradation. Still, sector heterogeneities require tailored policy responses. The study emphasizes the need to synchronize energy efficiency policies with sectoral compositions in the face of sustainability trade-offs that accompany ASEAN’s growth.</p>