Pediatric heart failure is a complex disease occurring when cardiac output is unable to meet the metabolic demands of the body. With improved surgical interventions and medical therapies, survival rates have improved, and care has shifted from focusing on survival to optimizing quality of life and health outcomes. Based on current literature, this review addresses the nutrition needs of infants and children in heart failure and describes the pathophysiology and metabolic implications of this disease. The prevalence of wasting in pediatric heart failure has been reported to be as high as 86%, highlighting the importance of nutrition assessment through all stages of treatment to provide appropriate intake of energy, protein, and micronutrients. The etiology of malnutrition in pediatric heart failure is multifactorial and involves hypermetabolism, decreased intake, increased nutrient losses, inefficient utilization of nutrients, and malabsorption. Children in heart failure often present with tachypnea, tachycardia, fatigue, nausea, and vomiting and consequently may not be able to meet their nutrition requirements through oral intake alone. Nutrition support, including enteral nutrition and parenteral nutrition, should be considered an essential part of routine care. The involvement of multiple allied health professionals may be needed to create a feeding therapy plan to support patients and their families. With appropriate nutrition interventions, clinical outcomes and quality of life can be significantly improved.