Pediatric patients undergoing cardiothoracic surgery are at increased risk for health care–associated infections, especially surgical site infections (SSIs). Delayed sternal closures are associated with prolonged lengths of stay and contribute to infection risks and morbidities. At a single-site academic pediatric center, we created an SSI-prevention bundle targeting the preoperative, intraoperative, and postoperative care periods. Using standard criteria, we determined the epidemiology of SSIs and measured SSI rates per 100 procedures from 2017 through 2023 before and after bundle implementation. Infections were predominantly caused by skin commensal bacteria. Despite an initial decrease in SSI rates for routine procedures and procedures with delayed sternal closures, there was no significant difference in SSI rates per 100 procedures during the preimplementation and postimplementation periods. However, compliance with bundle elements was preserved throughout the postimplementation period, including during the COVID-19 pandemic, which suggests that the use of the bundle is sustainable at our facility.