This study examined the relationship among nurses’ authentic leadership, psychological safety, and health promotion support. An online survey of Japanese nurses was conducted between March and April 2022, comprising items related to attributes, authentic leadership, psychological safety, leadership, and organizational health promotion support. Data drawn from 377 nurses’ responses were included in the analysis. Authentic leadership and psychological safety were significantly correlated with leaders’ health promotion support scores. The multiple regression analysis showed that leaders’ “Self-Awareness” was associated with “Feedback on physical condition from supervisors to personnel” and “Supervisors’ support for participating in health promotion efforts during work hours.” Meanwhile, leaders’ “Balanced Processing” was associated with “Communication about the importance of promoting a healthy workplace from supervisors to personnel.” Organizational “Programs and menus for improving health” and “Program and support for improving mental health” were also associated with nurses’ health promotion support. The findings suggest that encouragement from supervisors is associated with the health promotion of subordinates.