Purpose: This study aims to examine the effect of financial performance on firm value and evaluate the role of Good Corporate Governance (GCG) as a moderating variable. It hypothesizes that financial performance positively affects firm value, and GCG significantly strengthens this relationship. Research Method: A quantitative approach with an associative design was employed. The population comprised manufacturing companies listed on the Indonesia Stock Exchange (IDX) between 2020 and 2024. Using purposive sampling, 384 valid observations were collected from annual reports. Data were analyzed using Moderated Regression Analysis (MRA) via Stata. Financial performance was proxied by Return on Assets (ROA), firm value by Price to Book Value (PBV), and GCG was measured using a multidimensional Corporate Governance Index (CGI) extracted through Principal Component Analysis (PCA). Results and Discussion: The empirical results indicate that financial performance (ROA) has a positive and significant effect on firm value (PBV). Furthermore, the interaction test confirmed that CGI significantly moderates and strengthens the positive impact of financial performance on firm value. Implications: Practically, these findings urge corporate management to strategically synergize profit maximization with robust governance mechanisms to optimize shareholder wealth. Policymakers can use this insight to refine adaptive GCG regulations, while future researchers are encouraged to explore other sectors such as banking or energy. Originality: This study offers originality by utilizing a composite Corporate Governance Index (CGI) to capture post-pandemic business dynamics, addressing the multidimensionality gaps found in prior research that heavily relied on partial GCG proxies.