ABSTRACT: Firm value reflects a company’s ability to generate sustainable economic benefits. Drawing on agency theory, this study examines the role of good corporate governance (GCG) and audit quality in influencing firm value, with tax avoidance as a mediating variable. Effective governance and high-quality audits are expected to reduce managerial opportunism, including excessive tax avoidance, thereby enhancing investor confidence and firm value. Using purposive sampling, this study analyzes 27 mining companies listed on the Indonesia Stock Exchange over the 2021–2024 period, resulting in 108 firm-year observations. Data were obtained from annual reports and analyzed using multiple linear regression with Stata 17. The results show that GCG has no significant effect on firm value, while audit quality and tax avoidance significantly affect firm value. GCG does not influence tax avoidance, whereas audit quality significantly affects tax avoidance. Furthermore, tax avoidance does not mediate the relationship between GCG, audit quality, and firm value. These findings highlight the critical role of audit quality in enhancing firm value and controlling tax avoidance practices, providing important implications for managers, investors, and regulators in the mining sector.

KEYWORDS – Good Corporate Governance; Audit Quality; Firm Value; Tax Avoidance.