This study examines the effect of sustainability reporting on firm value, with profitability as a mediating variable, among energy sector companies listed on the Indonesia Stock Exchange during 2020–2024. Sustainability reporting is measured using the Sustainability Report Disclosure Index (SRDI), profitability is proxied by Return on Assets (ROA), and firm value is measured using Price-to-Book Value (PBV). This study applies a quantitative approach using secondary data from annual financial statements and sustainability reports. The sample was selected through purposive sampling, resulting in 95 observations. Data analysis was conducted using multiple linear regression and mediation testing with the Sobel test. The results indicate that sustainability reporting has a positive and significant effect on profitability and firm value. Profitability also has a positive and significant effect on firm value. Furthermore, profitability significantly mediates the relationship between sustainability reporting and firm value, demonstrating a partial mediation effect. These findings suggest that sustainability reporting enhances firm value not only through positive market perceptions but also indirectly by improving corporate profitability. The novelty of this study lies in integrating sustainability reporting, profitability, and firm value within a mediation framework in Indonesia’s energy sector during the 2020–2024 period. The findings highlight the importance of improving sustainability disclosure quality, transparency, and consistency while embedding sustainability practices into business strategies to strengthen financial performance, investor confidence, and long-term sustainable value creation.