It is well-established that different leadership styles are associated with followers' mental health. However, little is known about the relative strength of the relationship of different leadership styles with followers' mental health. So far, there is no meta-analysis comparing the incremental contribution of different leadership styles to mental health and studying potentially problematic construct proliferation. We included studies that compared at least two leadership styles in view of their relationships with followers' mental health and directly estimated the relative contribution of seven leadership styles (i.e., transformational, transactional, laissez-faire, task-oriented, relationship-oriented, and destructive leadership, as well as leader-member exchange) to followers' mental health. Using meta-analytical regression models, we compared the strength of the relationships between these leadership styles and followers' overall mental health as well as positive (well-being and psychological functioning) and negative aspects of their mental health (affective symptoms, stress, and health complaints). Fifty-three studies with 217 effect sizes comprising 93,470 participants met the inclusion criteria. Transformational and destructive leadership were the strongest predictors of overall and negative aspects of mental health among followers. In contrast, the strongest predictors of positive mental health outcomes among followers were relations-oriented and task-oriented leadership, followed by transformational leadership. In sum, our results suggest that various leadership styles make unique contributions to explaining followers' mental health and thus construct proliferation mostly does not pose a major problem when predicting relevant outcomes in this domain of leadership research. Our results are relevant for leadership development programs and for future organizational leadership models.