Women are still significantly underrepresented in management positions, even though they have been able to increase their share to a small extent in recent years. Using arguments derived from signalling theory, this study examines whether organisational family-friendly flexible working arrangements (FFWAs) help to increase internal promotions of women to supervisory or managerial positions and thus reduce the existing gender leadership gap. This effect is investigated using longitudinal data for German workplaces and employees covering 1631 firms and 314,201 employees and fixed effects logistic regression models. The results demonstrate that the implementation of FFWAs improves the chances of internal promotions to supervisory or managerial positions for employees, with women and men benefiting equally. However, if I use a broader definition that also includes highly qualified specialist roles, implementing FFWAs can provide better promotion opportunities for women. Second, FFWAs increase the likelihood of being promoted to managerial positions with reduced working hours, and this effect is slightly stronger for men. Third, surprisingly, no significant positive effects of FFWAs were found on mothers’ promotion of managerial positions. These results show that, even with organisational support, it remains difficult for women to reach management positions and combine family and career at the same time.