INTRODUCTION: Former stoma-site incisional hernia (FSH) is a common complication after ostomy reversal, with a variable reported incidence of up to 50%. Current literature suggests that FSH is underreported due to the lack of a definitive understanding of the timeline of its occurrence and recurrence, making FSH prevention a clinical dilemma. This study identifies FSH risk factors and diagnostic timeline to aid surgeons' clinical decision-making. METHODS: A retrospective chart review was conducted on 340 patients who underwent ostomy reversal between January 1, 2016, and December 31, 2021. Data collected include demographics, medical history, course of ostomy treatment, and hernia diagnosis. Logistic regression and Kaplan-Meier analysis were used to identify risk factors and understand the timeline of hernia occurrence. RESULTS: The total incidence of hernia, including patients who had a parastomal hernia before ostomy reversal, FSH after reversal, or both, was 38.8%. The incidence of former stoma-site hernia alone was 24.4%. Significant risk factors identified were elevated BMI, presence of parastomal hernia, hypertension, diabetes, immunosuppression, and the emergency nature of the case. Kaplan-Meier analysis showed that patients with either parastomal hernia prior to ostomy reversal or obesity had a greater than 35% likelihood of being diagnosed with FSH within the first 2 years following reversal. Other risk factors, including chemotherapy, radiation therapy, ostomy history, hernia history, smoking, and type of ostomy, lacked significance. The median time between ostomy reversal and the first FSH diagnosis was 295 days, and 84.3% of the cases were diagnosed within the first 2 years. CONCLUSION: Patients with ostomy are at substantial risk of developing FSH throughout the entire span of ostomy treatment. Patients with a high BMI, a parastomal hernia before ostomy closure, diabetes, and hypertension are at even higher risk of developing FSH.