This concept analysis study identified attributes and defined psychiatric nursing competency among psychiatric nurses. The approach of Walker and Avant was used for concept analysis, and a literature review was completed including eight steps. The concept of psychiatric nursing competency was identified as five attributes: professional assessment, situation coping skills, communication, cooperation, and self-management. Antecedents of the concept were psychiatric nursing education and experience, and the consequences were patient outcomes, patient safety, and efficiency of care. Psychiatric nursing competency was defined as the comprehensive ability to care for psychiatric patients appropriately and effectively in the nursing situation. This study is meaningful in that it clarified psychiatric nursing competency among psychiatric nurses, and the attributes and empirical referents of this study will be the basis for development to a psychiatric nursing competency measurement tool.