Purpose: This research aims to investigate the relationship between Environmental, Social, and Governance (ESG) performance and capital structure, using Debt-to-Equity Ratio (DER) and Debt-to-Asset Ratio (DAR) proxies, in Indonesia and Malaysia. The study seeks to address the gap in the literature by exploring how ESG factors influence the capital structure decisions of both financial and non-financial companies in these countries. Additionally, the research analyzes the impact of ESG performance on the cost of equity and cost of debt. Methods: The research utilizes secondary data extracted from annual reports and sustainability reports spanning from 2015 to 2020. A total of 102 companies, comprising 59 Indonesian companies and 52 Malaysian companies registered on CSRHub, are included in the analysis. ESG performance is assessed based on community, environmental, social, and governance indicators. Capital structure is measured using DER and DAR proxies. Statistical analysis techniques are employed to examine the relationship between ESG performance and capital structure, as well as its impact on the cost of equity and cost of debt. Results and Discussion: The research findings indicate that community, environmental, social, and governance performance exhibit a negative effect on the cost of equity, suggesting that companies with stronger ESG performance experience lower costs of equity financing. However, these ESG factors do not significantly affect the cost of debt. This implies that while ESG performance may influence equity holders' perceptions of risk and return, it may not have a direct impact on the cost of debt financing for companies in Indonesia and Malaysia. Implications of the Research: The results of this research have important implications for companies, investors, and policymakers interested in understanding the relationship between ESG performance, capital structure decisions, and financing costs. By demonstrating the impact of ESG factors on the cost of equity, the findings underscore the importance of integrating sustainability considerations into financial decision-making processes. Moreover, the research highlights the need for further investigation into the mechanisms through which ESG performance influences capital structure and financing costs. Originality/Value: This study contributes to the literature by offering novel insights into the relationship between ESG performance and capital structure in Indonesia and Malaysia. By examining the impact of ESG factors on both equity and debt financing costs, the research expands our understanding of how sustainability considerations influence corporate financial decisions. The findings provide valuable guidance for companies seeking to enhance their ESG performance and optimize their capital structure, ultimately contributing to more sustainable and responsible business practices in emerging markets.