AimTo understand the role adaptation process of nurses caring for older adult patients with terminal diseases in Chinese geriatric hospitals.BackgroundThe Chinese government has been encouraging the conversion of secondary general hospitals and some tertiary hospitals into specialized geriatric hospitals; however, research on nurses’ adaptation to caring for older adult patients with terminal diseases in these hospitals is lacking.MethodsIndividual in‐depth interviews were conducted with 13 registered nurses with a minimum of two years of experience caring for older adults with terminal diseases. Following Glaserian grounded theory, open, selective, and theoretical coding were conducted for data analysis. The study followed the Consolidated Criteria for Reporting Qualitative Research checklist.Results“Guards of the shining sunset” emerged as the core category. Participants experienced three stages: “chaotic me,” “rational me,” and “inclusive me.” They highlighted two causes, three contexts, two intervention conditions, three strategies, and two consequences.ConclusionThe study shows that nurses play a key role in “guarding the shining sunset” of older adult patients with terminal diseases. The observed role adaptation process provides theoretical support for interventions to assist nurses in becoming inclusive “guards of the shining sunset.”Implications for nursing practice and policyNurses play a unique role as guardians protecting the end‐of‐life quality of elderly patients. Their role needs to be expanded and strengthened via effective coping strategies and comprehensive legal, education, welfare, and professional promotion support policies. The substantive theory offered by this study may be applied by nurses, department leaders, geriatric hospital managers, and national‐level institutions to underpin future interventions and improve role adaptation.