<p>This study examines whether the influence of boardroom gender heterogeneity on corporate performance differs between family and non-family companies. We also investigate the role of CEO duality in this relationship. To this aim, we utilize a sample of Greek companies during the 2008–2020 period. Our results indicate that a U-shaped curve describes the relation between boardroom gender diversity and the performance of family companies. Also, the U-curve flattens when the CEO holds the chairman position. However, when splitting the sample into two subperiods (during and after the long-lasting socioeconomic crisis in Greece), the results persist only during the period of socioeconomic crisis. Regarding companies not controlled by families, the findings show that boardroom gender diversity does not affect their performance. This finding remains consistent regardless of the socioeconomic conditions. Overall, our findings are valid across different measures of boardroom gender heterogeneity and alternative econometric methodologies. Our conclusions enrich the corporate governance literature and family business research and have practical implications for policymakers in Greece.</p>