Extant literature on board gender diversity focuses on the main pillars of sustainability while ignoring the important subdimension – waste management. Using a sample of 8365 firm-year observations for the period 2002–2017 from 37 countries, we provide novel empirical evidence that board gender diversity significantly reduces (increases) waste generation (waste recycling) in firms. We also note that the impact is significant with two or more female directors and is primarily driven by female directors’ independence. Moreover, the relationship is moderated by the masculinity dimension of national culture and sustainable compensation policies. Our analysis also shows that waste management activities of gender-diverse boards accompany the better financial performance. Our findings are robust to several identification strategies and estimation techniques. Our study provides new insights into the governance–sustainability nexus and presents important policy implications for regulators across countries.