Purpose: Little is known about the impact of family caregiving for adults with poor prognosis cancer on caregivers’ own individual self-care practices. We explored differences in caregivers’ discrete self-care practices associated with varying levels of caregiver well-being, preparedness, and decision-making self-efficacy. Methods: Cross-sectional survey within eight community-based southeastern U.S. cancer centers was conducted. Family caregivers of Medicare beneficiaries ≥65 years with pancreatic, lung, brain, ovarian, head and neck, hematologic, or stage IV cancer completed measures of individual self-care practices (health responsibility, physical activity, nutrition, spiritual growth, interpersonal relations, stress management, and sleep), well-being (anxiety, depression, and health-related quality of life [HRQoL]), preparedness, and decision-making self-efficacy. Results: Caregivers (n = 294) averaged 66 years, were mostly female (72.8%), white (91.2%), Protestant (76.2%), retired (54.4%), and patients’ spouse/partner (60.2%). Approximately, half were rural-dwellers (46.9%) with incomes <$50,000 (53.8%). Most provided support 6–7 days/week (71%) for >1 year (68%). Nearly a quarter (23%) reported high depression and 34% reported borderline or high anxiety. Low engagement in all self-care practices was associated with worse caregiver anxiety, depression, and mental HRQoL (all p values < .05). Caregivers with lower health responsibility, spiritual growth, interpersonal relation, and stress management scores had lower preparedness and decision-making self-efficacy. Conclusions: A significant proportion of caregivers simultaneously report low engagement in all forms of self-care practices, high depression and anxiety, and low HRQoL mental health scores. Caregiver well-being, preparedness, and decision-making self-efficacy might be optimized through interventions targeted at enhancing health responsibility, stress management, interpersonal relationships, and spiritual growth self-care practices.