Against the background of legal amendments and society’s call for more gender-specific equality, this article examines the relationship between gender diversity in the supervisory board and its monitoring effectiveness. We test the aforementioned relationship based on agency theory and resource dependence theory and on the basis of several company-fixed panel regressions. The underlying panel data comprises 1500 supervisory boards of 132 companies listed in HDAX and SDAX between 2015 and 2017 (396 company years). Gender diversity is operationalized through different diversity metrics, and monitoring effectiveness is measured by excessive board compensation. The results indicate that a higher representation of women on the supervisory board (shareholder representatives and all members) is accompanied by lower excessive compensation and thus better monitoring effectiveness. In contrary, we cannot find a relationship between gender diversity of employee representatives or all members of the compensation committee and monitoring effectiveness. After international research has already dealt occasionally with this context, it is now being tested for the first time in the context of the dualistic corporate governance-system to what extent gender diversity in the supervisory board and the remuneration-related monitoring effectiveness are linked. Our paper argues that greater gender diversity, regardless of socio-political considerations, can be beneficial for companies’ corporate governance and thus contributes to the discussion about the impact of the statutory gender quota.