An updated systematic review with meta-analysis comparing perioperative prophylactic administration of corticosteroids with placebo in pediatric cardiac surgeries using cardiopulmonary bypass was conducted. The Cochrane Central Register of Controlled Trials and MEDLINE (via PubMed) were searched for relevant randomized controlled trials published between January 1, 2000, and February 14, 2023. The primary outcome was postoperative in-hospital mortality. Secondary outcomes were duration of mechanical ventilation, length of intensive care unit and hospital stay, postoperative low cardiac output syndrome, and adverse events. A total of 11 studies were included in the meta-analysis. Corticosteroid administration did not decrease postoperative in-hospital mortality compared with placebo (relative risk, 0.69; 95% confidence interval, 0.40-1.17). Subgroup analyses according to the type of corticosteroids and neonates revealed that corticosteroids did not decrease postoperative in-hospital mortality. In the trial sequential analysis, the last point in the z-curve was within the futility borders. Although the duration of mechanical ventilation (mean difference, −5.54 h; 95% confidence interval (CI), −9.75 – −1.34) and incidence of low cardiac output syndrome (relative risk, 0.75; 95% CI, 0.59 – 0.96) decreased with corticosteroid administration, it did not affect the length of intensive care unit (mean difference, −0.28 days; 95% CI, −0.74 – 0.17) and hospital stay (mean difference, −0.59 days; 95% CI, −1.31 – 0.14). In conclusion, perioperative prophylactic corticosteroid administration in pediatric cardiac surgeries using cardiopulmonary bypass did not decrease postoperative in-hospital mortality compared with placebo. According to the trial sequential analysis results, additional randomized controlled trials assessing mortality are not required.