Will carbon emission disclosure increase firm value in Vietnam? The mediating role of audit quality

Growing global pressure for environmental accountability has increased the demand for credible carbon reporting. This study examines how Carbon Emission Disclosure (CED) affects Firm Value (FV) and emphasize how Audit Quality (AQ) helps shape that relationship in Vietnam’s emerging market. Using balanced panel data from 145 non-financial listed firms from 2015 to 2022, we apply OLS and Quantile Regression to ensure strong and reliable results. Our findings show that CED has a positive and meaningful impact on FV. Furthermore, AQ, measured by Big 4 assurance, plays a critical mediating role. Indeed, when firms are audited by a Big 4 company, the direct effect of CED on FV drops by about 35%, clearly showing the “credibility premium” that investors assign to verified information. We also find that the impact of CED becomes even stronger after regulatory changes (up by 49.7%) and during the COVID-19 pandemic (up by 37.8%), suggesting that investors pay closer attention to trustworthy disclosures during periods of uncertainty. This study adds to existing theory by showing that in markets with weak institutional systems, transparency alone is not enough—firms need credible, assured disclosures to create real economic value. In practice, the results highlight that verified carbon reporting is not just compliance; it is a strategic investment. For policymakers, the findings support the need for phased verification requirements to guide emerging countries, which are under the shift toward a low-carbon economy.