Background: The family often takes care of an elderly person who suddenly becomes dependent. This greatly affects different aspects of the caregivers’ lives. The aim of this study is to explore the initial experiences, during the first year of care, of persons who suddenly become caregivers for elderly dependent relatives. Methods: A search in CINAHL, PsycINFO, WOS, Medline, and Scopus and a metasynthesis of qualitative research were conducted including 19 articles. Results: Three categories were developed to explain the process of becoming a caregiver ‘taking on the role’ (life changes, uncertainty and confusion, and acceptance or resistance); ‘beginning to realise’ (new needs, impact, and appraisal); and ‘implementing strategies’ (seeking help and self-learning, reordering family and social relationships, solving problems, and devising strategies to decrease negative emotions and stress). Conclusions: The synthesis provides a comprehensive understanding of the experience of becoming a caregiver in order to help health-care professionals to adapt care plans to this situation.