Abstract Background Patients with heart failure (HF) and their family caregivers have interdependent relationships in managing HF. Shared care within dyads refers to interpersonal interactions characterized by exchanging care and support in chronic illness management. High levels of shared care improve patients’ health outcomes, but it is unclear if shared care is equally beneficial for caregivers. Also unknown is how shared care contributes to the outcomes of both dyad members. We propose that perceived control may be critical in the link between shared care and health status for dyads. Thus, the purpose of this study was to determine whether perceived control over one’s health mediates the association between shared care and physical and mental health in patients with HF and their caregivers. Method Patients with HF and their primary caregivers (N=151 dyads) completed questionnaires in this cross-sectional study. Shared care, perceived control over one’s own health, and health status were assessed using the three subscales of the Shared Care Instrument (i.e., communication, decision-making, and reciprocity), the Cardiac Attitudes Scale-Revised, and the Medical Outcomes Study Health Survey-36, physical and mental health scales, respectively. A series of actor-partner interdependence models with mediation dyadic analyses were conducted. Results Patients with HF (mean age 60.3 Years, 64% male) and their caregivers (mean age 56.6 years, 75% female) reported similar levels of communication and reciprocity in shared care, but patients reported higher scores of decision-making in shared care than their caregivers (P < .001). Perceived control over one’s own health significantly mediated the association between communication and physical health (indirect actor effect = .1487; 95% CI: 0.0478 to 0.2759) and between communication and mental health (indirect actor effect = .1650; 95% CI: 0.0454 to 0.3260) for patients, not caregivers (Figures A1 & A2). Similarly, perceived control significantly mediated the association between reciprocity and physical and mental health for patients, not caregivers (Figures B1 & B2). Perceived control mediated the association of decision-making with physical health and mental health for caregivers, not patients (Figures C1 & C2). Conclusion Higher levels of communication and reciprocity increased patients’ perceived control, ultimately improving their physical and mental health, whereas caregivers’ decision-making improved their health by enhancing their perceived control over their health. The different patterns of shared care are linked to the health of patients and caregivers by enhancing perceived control over one’s health.Figure A & BFigure C