Objectives: We reviewed the existing definitions of psychological frailty and provided a comprehensive overview of the concept and associated measurements. Study Design and Setting: We followed the PRISMA guidelines for scoping reviews and the Joanna Briggs Institute Manual for Evidence Synthesis. The eligibility criteria for including studies were developed based on the participants-concept-context framework. We searched the Cumulative Index to Nursing and Allied Health Literature, Scopus, PubMed, Web of Science and PsycINFO databases, and other sources for relevant studies published between January 2003 and March 2022. Results: The final scoping review included 58 studies. Of these, 40 defined psychological frailty, seven provided a novel definition, and 11 focused on the components defining psychological frailty. We proposed four groups of components to better characterize psychological frailty: mood, cognitive, other mental health, and fatigue-related problems. We identified 28 measuring tools across studies, and the Tilburg Frailty Indicator was the most frequently used (46.6%). Conclusion: Psychological frailty is a complex concept whose definition seems to lack consensus. It could include both psychological and physical features. Depression and anxiety are commonly used to define it. This scoping review outlined future research directions for refining the concept of psychological frailty.