While Environmental, Social, and Governance (ESG) management has emerged as a global strategic priority, the tension between high ESG performance and internal distributive fairness remains a critical yet underexplored area. This study investigates the association between ESG ratings and the executiveemployee pay gap, while examining the moderating influence of internal and external monitoring mechanisms. Utilizing a longitudinal dataset of 3,499 firm-year observations from listed non-financial Korean firms (2013–2023), we perform regression analyses integrating ESG ratings from the Korea ESG Standards Institute (KCGS) with mandatory executive compensation disclosures. The empirical results reveal a significant positive association between ESG ratings and the executive-employee pay gap. This suggests that superior ESG performance may be leveraged as a justification for excessive executive compensation, potentially exacerbating internal income inequality. However, this positive relationship is significantly attenuated in firms with higher analyst coverage or greater ownership concentration by controlling shareholders. These findings indicate that robust internal and external monitoring serves as a vital constraint, preventing firms from utilizing proactive ESG engagement as a mechanism for executive rent extraction. This research contributes to Managerial Power Theory by illustrating the potential decoupling between external social performance and internal pay equity.