Purpose – The purpose of this study is to investigate the association between anti-corruption disclosure (ACD) and firm value and explore the role of country risk as a determinant of disclosure practices and a moderator of the relationship between ACD and firm value. This study focuses on firms operating in Southeast Asia under the ASEAN regional framework, specifically the ASEAN-5 countries (Indonesia, Malaysia, Singapore, Thailand and the Philippines), which offer insights into emerging markets with diverse institutional frameworks. Design/methodology/approach – A quantitative research design is used with data from publicly listed firms in ASEAN-5 countries, obtained from the Refinitiv Eikon database for the period 2013–2017. Panel data regression techniques are used to test the hypotheses. Country risk is proxied using components of the International Country Risk Guide, such as political stability, regulatory quality and control of corruption. Findings – The results of this study reveal that ACD has a negative impact on firm value, contrary to expectations. This finding of this study suggests that the relatively low level of disclosure among the sampled firms reduces its effectiveness as a signal of transparency. However, country risk positively moderates the relationship between ACD and firm value, suggesting that a stable institutional environment enhances the credibility and impact of these disclosures. Furthermore, country risk significantly influences the level of ACD, with firms in low-risk environments more likely to engage in comprehensive reporting. Practical implications – These findings highlight the importance of institutional quality in shaping the effectiveness of corporate ACDs. Policymakers in ASEAN-5 countries should focus on strengthening governance frameworks to promote transparency and mitigate corruption risks. For corporate leaders, these results underscore the need to tailor disclosure strategies to align with the institutional environment, particularly in high-risk contexts where credibility challenges may arise. Social implications – By highlighting the role of country risk in enhancing the effectiveness of ACDs, this study underscores the broader societal benefits of improving institutional quality. A strengthened institutional framework can promote transparency, reduce corruption and enhance investor confidence, contributing to sustainable economic development. Originality/value – This study contributes to the literature by providing an understanding of how the institutional environment affects the credibility and effectiveness of corporate ACDs. This study extends the application of signaling theory to governance practices in emerging markets and highlights the contextual nature of corporate transparency. © 2026 Emerald Publishing Limited