Aims Heart Failure (HF) self-care improves patient outcomes but trials designed to improve HF self-care have shown inconsistent results. Interventions may be more effective in improving self-care if they mobilize support from providers, promote self-efficacy, increase understanding of HF, increase the family involvement, and are individualized. All of these elements are emphasized in motivational interviewing (MI); few trials have been conducted using MI in HF patients and rarely have caregivers been involved in MI interventions. The aim of this study will be to evaluate if MI improves self-care maintenance in HF patients, and to determine if MI improves the following secondary outcomes: a) in HF patients: self-care management, self-care confidence, symptom perception, quality of life, anxiety/depression, cognition, sleep quality, mutuality with caregiver, hospitalizations, use of emergency services, and mortality; b) in caregivers: caregiver contribution to self-care, quality of life, anxiety/depression, sleep, mutuality with patient, preparedness, and social support. Methods A three-arm randomized controlled trial will be conducted in a sample of 240 HF patients and caregivers. Patients and caregivers will be randomized to the following arms: 1) MI intervention to patients only; 2) MI intervention to patients and caregivers; 3) standard of care to patients and caregivers. The primary outcome will be measured in patients 3 months after enrollment. Primary and secondary outcomes also will be evaluated 6, 9 and 12 months after enrollment. Conclusion This study will contribute to understand if MI provided to patients and caregivers can improve self-care. Because HF is rising in prevalence, findings can be useful to reduce the burden of the disease.