Background: Nurse managers are central to guaranteeing quality healthcare outcomes. However, their position is very demanding and special attention should be paid to their mental well-being. Good mental well-being at work is associated with overall occupational well-being, increasing nurse managers' intention to stay in the profession and their commitment to their organization. However, little is known about nurse managers' personal and work-related resources that support good mental well-being. Objective: To explore work-related and personal resources associated with nurse managers' work engagement and mental well-being. Design: A cross-sectional survey study. Participants: Finnish nurse managers (n = 366) including ward managers (n = 332), chief nurses (n = 24), and administrative head nurses (n = 6). Methods: Nationwide online survey data was collected with a self-administered questionnaire in February 2023 from the members of one health and social care workers' trade union. The relationships between nurse managers' personal (psychological capital and calling) and workrelated (job resources and social support) resources, work engagement and mental well-being were analysed using structural equation modeling. Nurse managers were also divided into two groups based on their mental well-being score: those with and without depression. The study is reported following the guidelines for Strengthening the Reporting of Observational Studies in Epidemiology (STROBE). Results: Nurse managers who had depression (27%) were associated with less personal and workrelated resources compared to managers without depression. Work engagement correlated strongly with mental well-being. A structural equation model that indicated positive significant total effects of work engagement (& beta; = 0.38), social support (& beta; = 0.26), job resources (& beta; = 0.19), and psychological capital & beta; = 0.28) and calling (& beta; = 0.13) with mental well-being had an excellent fit. Conclusion: Nurse managers' mental well-being can be supported by organisational strategies and national policies that enhance leadership skills and increase work-related resources, which, in turn, can manifest as psychological and professional capital and a sense of meaningfulness in work.