Background: Ovarian endometrioma is a common manifestation of endometriosis and associated with a high risk of postoperative recurrence. Bilateral involvement is often considered a marker of more severe disease; however, evidence comparing recurrence risk between unilateral and bilateral endometrioma following combined surgical and hormonal therapy remains limited.Methods: Retrospective cohort study was conducted involving 1,073 women diagnosed with ovarian endometrioma who underwent conservative surgery followed by leuprolide acetate therapy between 2021 and 2024. Recurrence was defined as the reappearance of endometriotic ovarian cysts detected by transvaginal ultrasonography during follow-up. Demographic and clinical characteristics were analyzed using univariate and bivariate methods, including Chi-square tests. Multivariate Cox proportional hazards regression was performed to identify independent predictors of recurrence, with hazard ratios (HRs) and 95% confidence intervals (CIs) reported.Results: The overall recurrence rate was 32.2%. Recurrence occurred more frequently in patients with bilateral endometrioma compared with unilateral involvement (41.1% vs 26.1%, p < 0.001). Bivariate analysis demonstrated significant associations between recurrence and laterality, age, body mass index, cyst size, deep infiltrating endometriosis (DIE) grade, surgical technique, and postoperative hormonal add-on therapy (all p < 0.001). In multivariate Cox regression analysis, bilateral endometrioma remained an independent risk factor for recurrence (HR 2.77; 95% CI 2.12–3.62). Severe DIE, infertility, and multilocular cysts were also associated with increased recurrence risk. Conversely, postoperative hormonal add-on therapy showed a protective effect against recurrence (HR 0.87; p < 0.05).Conclusion: Bilateral ovarian endometrioma is associated with a significantly higher risk of postoperative recurrence compared with unilateral disease, even after combined surgical and leuprolide acetate therapy. The use of postoperative hormonal add-on therapy appears to reduce recurrence risk. These findings support risk-stratified postoperative management and emphasize the importance of individualized hormonal strategies, particularly in patients with bilateral disease.