Aim. We investigated the impact of empowering leadership on both perceived stress and salivary cortisol, a commonly utilized biological indicator for stress assessment. Background. Empowering leadership is gaining increasing interest in companies. However, the impact of empowering leadership on stress is still insufficiently explored, with conflicting findings within the literature on this topic. While certain studies indicate that empowering leadership reduces perceived stress, other studies have suggested that empowering leadership could be stressful. Methods. We conducted a cross-sectional study using a questionnaire among a sample of 397 participants working in a French hospital. Participants’ salivary cortisol was assessed. All analyses exploring the relationships between empowering leadership, perceived stress, and salivary cortisol were performed using multiple imputation methods. Results. Empowering leadership could simultaneously increase and decrease perceived stress. Specifically, although the empowering leadership global factor showed a negative correlation with perceived stress, some specific empowering leadership behaviors were positively associated with perceived stress. However, salivary cortisol was positively related to perceived stress and strictly negatively related to empowering leadership. Furthermore, salivary cortisol could be explained by a significant interaction effect between perceived stress and empowering leadership, indicating that empowering leadership enables employees to cope with perceived stress. Conclusions. Although empowering leadership was an ambiguous antecedent of perceived stress, our findings suggested that empowering leadership was a protective factor against increased salivary cortisol. These results suggest that empowering leadership behaviors could prevent biological stress. Implications for Nursing Management. While empowering leadership showed a protective effect on salivary cortisol, it is essential for managers to adopt the full set of empowering leadership practices to guarantee protective effects on perceived stress. This trial is registered with NCT04010773.