This research examines the effect of carbon emissions disclosure on company performance, with company size as a moderating variable. As global awareness of environmental sustainability increases, companies are increasingly under pressure to disclose their carbon emissions. This study analyzes how these disclosures affect company performance, as measured by Tobin's Q. In addition, this study also explores whether company size strengthens or weakens this relationship. Using a sample of 200 companies that have had an IPO, all existing data comes from sustainability reports and financial reports, the research results show that carbon emissions disclosure has a significant positive influence on company performance. In addition, company size weakens the positive impact of carbon emissions disclosure, indicating that all companies (large and small), can take advantage of environmental transparency to improve company performance. This study shows that, as control variables, leverage, board size significantly improve company performance, while age and board independence have a minimal impact on company performance. These findings contribute to the growing literature on corporate sustainability and provide insights for policymakers and managers aiming to balance environmental responsibility with financial success.