Background: Patients submitted to cardiac surgery are more susceptible to surgical site infection. Prevention of this infection is based on a bundle of preventive measures. Aim: Investigate the effect of implementing evidence-based care bundle on healthcare providers' practices, and the prevalence of surgical site infections among cardiac surgery patients. Design: A quasi-experimental research design (study and control groups, pre and posttest). Setting: Cardiothoracic Surgery Department, Outpatient Unit, Operating Theater, and Cardiothoracic Intensive Care Unit at Assiut University Heart Hospital. Participants: A convenience sample of 40 healthcare providers & a purposive sample of 100 patients, which divided into two equal groups. Tools: (I) Cardiac surgical patient assessment form, (II) Self- administered Questionnaire for Healthcare Providers, and (III) National Nosocomial Infections Surveillance System Risk Index. Results: The overall score for healthcare providers' practices showed a significant improvement, increasing from 17.45 ± 1.32 to 25.65± 3.80 after the implementation of evidence-based care bundle. There was a highly statistically significant difference was observed between the two groups regarding the degree of wound contamination with (p.value=0.005**), and regarding the National Nosocomial Infection Surveillance Risk Index with (p.value=0.001**). Conclusion: A significant improvement in healthcare providers' practices regarding preoperative, intraoperative, and postoperative measures following training on evidence-based care bundle, resulting in a lower surgical site infection prevalence in the study group compared to the control group. Recommendations: The National Nosocomial Infections Surveillance Risk Index should be routinely used as a predictive tool to assess the risk of surgical site infection in cardiac surgery patients.