In this paper, we examine the relationship between board gender diversity and environmental, social, and governance (ESG) decoupling and the moderating effect that religiosity has on this relationship. We utilise an international sample of 26,176 firmyear observations that cover the period from 2005 to 2019. Consistent with the upper echelon theory and the gender socialisation theory, we provide evidence that firms with a more gender-diversified board of directors tend to engage less in ESG decoupling, and this relationship is more pronounced among firms domiciled in countries with a low level of religiosity. We also find that the effect of religiosity on the relationship between board gender diversity and ESG decoupling is more pronounced for firms that engage in greenwashing and those operating in controversial industry sectors. Our study contributes to the growing debate on ESG decoupling, offering policy insights to regulators and policymakers into the role of board gender diversity and religiosity in reducing unethical managerial behaviour.