A retrospective study included 139 patients with congenital obstructive Müllerian anomalies and histologically confirmed ovarian endometrioma who underwent complete reconstruction of the lesion between January 20, 2003 and January 20, 2013, with a mean age of 20.70 ± 5.81 years. During a mean follow-up of 80.8 months, 29.5% of patients relapsed, with cumulative rates of 1.4% at 24 months, 10.1% at 36 months, 27.1% at 60 months, and 34.4% at 120 months. Multivariable Cox regression analysis identified independent risk factors for recurrence: preoperative hematoma > 5 cm³ (HR: 2.650, 95% CI: 1.356–5.17, p=0.004), rASRM score > 40 (HR: 3.488, 95% CI: 95.72%, p=0.017), non-operative pregnancy (HR: 5.329, 95% CI: 1.399–20.307, p=0.014) and hormone therapy ≤ 30 months (HR: 3.563, 95% CI: 1.707–7.439, p=0.001). Based on these factors, a predictive nomogram was developed, showing strong discriminatory power (5-year AUC=0.862, 10-year AUC=0.808) and good calibration. Internal validation using K-fold cross-validation confirmed robust performance (5-year AUC=0.864, 10-year AUC=0.800), with clinical utility according to decision curve analysis. The model enables risk stratification of ovarian endometrioma recurrence after surgery and supports personalized management, including early intervention and prolonged hormonal suppression.