The ASEAN-5 countries have been experiencing an upward trend in public debt, which can hinder their socioeconomic development, military and educational systems, among others. Prior research has not examined environmental degradation as a possible determinant of public debt in the region. To address this gap, this book investigates factors influencing public debt in the ASEAN-5 countries, including environmental degradation, economic growth and investment. We employ the Fully Modified Ordinary Least Square (FMOLS) method with data spanning from 1996 to 2021. Our findings suggest that, investment has a negative association with public debt, indicating that higher investment can help reduce public debt levels. Additionally, economic development and environmental degradation have a positive correlation with public debt, indicating that higher economic growth and environmental degradation can lead to increased public debt. These findings can provide valuable insights for policymakers to create economic and environmental policies that promote sustainable development in the ASEAN-5 region. The results differ in some variables when analyzing country by country, suggesting that policies should be adjusted to the fiscal and development peculiarities of each country. Overall, this book contribution lies in shedding light on the determinants of public debt and their interplay with environmental degradation, investment and economic growth in the region.