Objective <p>The Nuss procedure is widely applied for the treatment of pectus excavatum (PE); however, postoperative infection remains a significant concern. Herein, we evaluated the postoperative outcomes and risk factors for postoperative infections following the Nuss procedure.</p> Methods <p>This study comprised a retrospective review of 112 cases of PE treated via the Nuss procedure between January 2019 and March 2024. Postoperative infection control measures, including thorough disinfection of the surgical field and perioperative intravenous administration of cefazolin, were ensured in all cases. Patient characteristics, surgical outcomes, and postoperative complications were analyzed, and risk factors for postoperative infection were assessed via multivariate analysis.</p> Results <p>Postoperative complications were observed in 17 cases (15.2%), including 6 (5.4%) with infection. Atopic dermatitis (AD) was significantly more common in the infection group (4/6, 66.7%) than in the non-infection group (8/106, 7.6%, <i>p</i> &lt; 0.01). Multivariate analysis further identified the use of topical steroid medications for AD as the only independent risk factor for postoperative infection (Odds Ratio: 51.0, 95% CI: 7.12–366.0). Notably, two infections occurred beyond the typical 90-day surveillance period.</p> Conclusions <p>AD is a significant risk factor for postoperative infection following the Nuss procedure, particularly when managed with topical steroid medications. These results suggest that patients with AD undergoing this procedure require meticulous preoperative management, rigorous infection control measures, and extended follow-up owing to the continued risk of infection throughout the bar placement period.</p>