This study examines the influence of environmental, social, and governance (ESG) performance on financial metrics, specifically return on investment (ROI) and return on equity (ROE), with internal control systems (ICS) serving as a mediating variable. The descriptive and cross-sectional investigation concentrates on Fortune 500 corporations in India. Data were acquired through a survey comprising 23 adapted and modified scale items that evaluate six pivotal variables linked to ESG performance and financial metrics. The sample comprised 566 professionals, including chartered accountants, finance managers, and accountants, who were selected via purposive sampling. The results indicate that environmental, social, and governance scores positively and statistically significantly affect ESG performance. Furthermore, ESG performance significantly impacts ICS, ROI, and ROE. This research emphasises the essential function of effective internal control systems in augmenting the financial outcomes associated with robust ESG performance within Indian Fortune 500 firms.