Due to the high burden of depression, new models and methods of mental healthcare need to be developed. Prior research has shown the potential benefits of using technology tools such as mobile apps as self-help or combined with psychological treatment. Therefore, professionals should acquaint themselves with evidence-based apps to be able to use them with clients and guide the clients in their use. The purpose of this study was to explore how an acceptance and commitment therapy-based mobile app was perceived as a self-management tool among nurses, and how it could be applied in the prevention and treatment of depression and other mental health issues. Sixteen Finnish nurses undergoing depression nurse specialist education used the app for 5 weeks and participated in semistructured focus group interviews. Interviews were analyzed by qualitative content analysis. In general, the nurses found the app suitable as a self-management tool and identified three models of using it in clinical practice. Having used the app personally, the nurses were eager to take it into use with various client groups, especially in occupational health but also in the treatment of mental health problems. However, they also raised concerns about the effort needed in familiarizing oneself with the content and pointed out specific client groups for whom the benefits of the app should be carefully weighed against the potential risks. Despite the small sample size, the findings suggest that involving technology tools as part of the nurses' education could ease their adoption in clinical practice. The degree of professional support in the app use should be aligned to the severity of the mental health problems.