A restrictive blood transfusion strategy has emerged in adult cardiac surgery. However, the feasibility in children is poorly investigated. 352 consecutive patients undergoing open-heart surgery were retrospectively reviewed, excluding patients requiring extracorporeal membrane oxygenation. Patient demographics, perioperative blood product usage, and clinical outcome parameters were investigated. Variables predicting the need for blood products were delineated. Of the 352 study patients, 148 patients (42%) underwent bloodless surgery and 204 (58%) were transfused. Of the 204 transfused patients, 170 (83.4%) patients received one blood transfusion and 34 (16.6%) received two or more blood transfusions. Patient’s weight and preoperative hematocrit (Hct) were statistically significant in predicting the need for blood priming the CPB circuit (AUC 0.99, p < 0.001, sensitivity 96.6%, specificity 95.2%). A body weight of 8.5 kg carried a sensitivity of 100% and specificity of 94.5% (p < 0.001) for a blood prime. Among patients with a weight less than 8.5 kg (n = 171), only 27 patients (15.8%, p < 0.001) required additional transfusion of PRBCs. Factors impacting the need for a blood transfusion during CPB included redo surgery [odds ratio (OR) 4.61, p = 0.001] and the highest lactate level on CPB (OR 1.65, p = 0.006). Redo surgery had the highest impact (OR 7.27, p = 0.012) for requiring a postoperative PRBC transfusion. A restrictive transfusion strategy can be safely implemented in pediatric cardiac surgery. The majority of children with a BW > 8.5 kg required no blood products and those with a BW ≤ 8.5 kg required only 1 unit of blood, to prime the cardiopulmonary bypass circuit.