Surgical site infections (SSIs) following cardiothoracic surgery can pose significant challenges to patient recovery and outcome. This systematic review and meta-analysis aim to identify and quantify the risk factors associated with SSIs in patients undergoing cardiothoracic surgery. A comprehensive literature search adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and based on the PICO paradigm was conducted across four databases: PubMed, Embase, Web of Science and the Cochrane Library, without any temporal restrictions. The meta-analysis incorporated studies detailing the risk factors for post-operative sternal infections, especially those reporting odds ratios (OR) or relative risks with 95% confidence intervals (CI). Quality assessment of the studies was done using the Newcastle-Ottawa Scale. Statistical analysis was executed using the chi-square tests for inter-study heterogeneity, with further analyses depending on I2 values. Sensitivity analyses were performed, and potential publication bias was also assessed. An initial dataset of 2442 articles was refined to 21 articles after thorough evaluations based on inclusion and exclusion criteria. Patients with diabetes mellitus have an OR of 1.80 (95% CI: 1.40-2.20) for the incidence of SSIs, while obese patients demonstrate an OR of 1.63 (95% CI: 1.40-1.87). Individuals who undergo intraoperative blood transfusion present an OR of 1.13 (95% CI: 1.07-1.18), and smokers manifest an OR of 1.32 (95% CI: 1.03-1.60). These findings unequivocally indicate a pronounced association between these factors and an elevated risk of SSIs post-operatively. This meta-analysis confirms that diabetes, obesity, intraoperative transfusion and smoking heighten the risk of SSIs post-cardiac surgery. Clinicians should be alert to these factors to optimise patient outcomes.© 2023 The Authors. International Wound Journal published by Medicalhelplines.com Inc and John Wiley & Sons Ltd.