This study assesses the role of country characteristics on the association between board gender diversity and sustainability performance. It evaluates the significance and relevance of country characteristics in capturing the contextual sensitivity of the relationship between board gender diversity and sustainability performance. Using a sample of 5087 firms from 50 countries, the study establishes that the presence of females on corporate boards enhances sustainability performance. However, the strength of this relationship is contingent on the characteristics of the country within which a firm operates. Specifically, the positive relationship between board gender diversity and sustainability performance is more pronounced in countries with higher cultural orientations on individualism, uncertainty avoidance, indulgence, and femininity. More substantial financial development, an application of civil law and legal systems and weaker economic conditions in a country also facilitate female directors in enhancing sustainability performance. The study provides deeper insights into how country factors interact with gender on the board factor in leading the sustainability performance of firms.