Background: The angiotensin-converting enzyme inhibitor (ACEI) enalapril is often administered to infants and young children with heart failure (HF) in various dosing regimens and formulations not adapted for their age. Methods: This prospective, two-center, open-label 8-week study evaluated an age-appropriate formulation of orodispersible minitablets (ODMTs) of enalapril (0.25 mg and 1 mg) in children aged 0 to 6 years with HF due to congenital heart disease. An age/weight-based dosing schedule was followed. Measures of echocardiographic parameters, blood pressure, heart rate, modified Ross score, and biochemistry were obtained over the 8-week period. The following two groups were assessed: ACEI-naïve and ACEI-pretreated patients. Results: In total, 53 children (age range of 0.05 to 4.8 years) were enrolled and 29 were ACEI-naïve. The average enalapril dose was 0.098 mg/kg (0.06–0.17 mg/kg) in the naïve group and 0.15 mg/kg (0.07–0.3 mg/kg) in pretreated patients. After 8 weeks, the modified Ross score and left ventricular diastolic dimension (LVD) z-score showed a significant decrease in both groups (p < 0.005). During 8 weeks follow-up, there were no difference in the z-scores for the systolic blood pressure (p = 0.071) or heart rate (p = 0.146). Conclusions: Pediatric patients treated with ODMTs of enalapril for 8 weeks had favorable improvements in LVD and HF symptoms.