Various methods have been used to evaluate the predictivity of some markers during the recovery process after cardiac surgery in children. The aim herein was to evaluate the vasoactive ventilation renal (VVR) score in predicting the clinical outcomes of children who underwent congenital cardiac surgery within the early period in the pediatric intensive care unit (PICU). Patients who underwent congenital heart surgery (CHS) between November 2016 and March 2020 were enrolled and evaluated prospectively. The VVR score was calculated as follows: vasoactive inotrope score (VIS) + ventilation index + (change in serum creatinine level based on the baseline value × 10). The relationship between the duration of mechanical ventilation and the length of stay (LOS) in the PICU was evaluated via receiver operating characteristic (ROC) curve analysis and the cut-off values were calculated. At all of the time points identified in the study, the VVR score had a higher area under the ROC curve (AUC) when compared to the VIS and serum lactate levels, and the 48-h VVR score had the highest AUC (AUC 0.851, 95% confidence interval (CI) 0.761–0.942/LOS in the PICU; AUC 0.946, 95% CI 0.885–1.000/duration of mechanical ventilation). The 48-h VVR score for the LOS in the PICU was 6.7 (sensitivity 70%, specificity 92%) and that for the duration of mechanical ventilation was 9.1 (sensitivity 87%, specificity 97%). As a result, in our study, it was found that the VVR score is a new and effective predictor of the duration of mechanical ventilation and LOS in the PICU in postoperative CHS patients.