This study aims to investigate the impact of the presence of women on board, green accounting practices, and carbon emission disclosure on the firm value of heavily polluting companies in the Association of Southeast Asian Nations (ASEAN), with a focus on exploring the moderating effects of women on board. Employing an exploratory quantitative approach, secondary data including financial reports, sustainability reports, and environmental scores from the Bloomberg database were analyzed for 57 ASEAN companies over the period of 2017–2022. Tobin’s Q was utilized as a measure of firm value (Kurnia et al., 2021). This study develops the previous literature on gender diversity (Simionescu et al., 2021) and environmental issues (Al-Dhaimesh, 2020; Choi et al., 2013). The findings reveal that green accounting practices and carbon emission disclosure do not significantly correlate with the firm value, while the presence of women on board does. Moreover, women on board play a significant moderating role in the relationship between green accounting practices, carbon emission disclosure, and firm value. The study also discusses the implications of environmental performance practices on firm valuation based on these findings.