This paper examines the relationship between carbon emissions restatements and firm value. Using the carbon emissions data from the Carbon Disclosure Project (CDP) between 2011 and 2023, we document a negative relationship between carbon emissions restatements and firm value measured by Tobin’s Q. In particular, restatements of Scope 2 emissions, compared to restatements of Scope 1 emissions, have a stronger impact on firm value. In addition, we find that upward restatements of Scope 1 emissions are negatively associated with firm value, whereas both upward and downward restatements of Scope 2 emissions are negatively related to firm value. These findings indicate that investors are more sensitive to the credibility of indirect emissions disclosures (i.e., Scope 2 emissions), which are related to external parties and involve greater measurement complexity. We further find that external assurance attenuates the negative valuation effects of emissions restatements. For the reasons underlying carbon emissions restatements, we document that capital markets penalize restatements due to methodology changes. Overall, our results highlight the role of credible carbon reporting and assurance in firm valuation, particularly in this stringent regulatory context.