Background: This study aimed to evaluate the effectiveness of pelvic and para-aortic lymphadenectomy in patients with advanced epithelial ovarian cancer following neoadjuvant chemotherapy. Methods: This single-center retrospective study analyzed patients with advanced epithelial ovarian cancer who underwent interval debulking surgery between December 2008 and March 2020. Patients’ clinical and pathological data were obtained from medical records. Statistical analyses were performed using the Fisher’s exact and Mann–Whitney U test. Results: Overall, 33 and 22 patients were included in the lymphadenectomy and no-lymphadenectomy groups, respectively. The lymphadenectomy group had longer operative time and higher rates of intraoperative blood loss and lymph cysts than the no-lymphadenectomy group (p 0.0001). The median progression-free survival (PFS) was longer in the lymphadenectomy group than in the no-lymphadenectomy group (37.0 vs. 20.0 months, p = 0.038). Among patients with enlarged lymph nodes before chemotherapy, the median PFS was longer in the lymphadenectomy group than in the no-lymphadenectomy group (36.0 vs. 15.0 months, p = 0.013). Multivariate analysis of all patients revealed that residual tumor status (p = 0.002) and histology (p = 0.009) were associated with PFS. Additionally, multivariate analysis of patients with enlarged lymph nodes before chemotherapy showed that lymphadenectomy (p = 0.017) and histology (p = 0.021) were associated with PFS. Conclusions: Systematic lymphadenectomy was associated with complications; however, PFS was significantly prolonged in patients with enlarged lymph nodes in the lymphadenectomy group. Therefore, lymphadenectomy has the potential to improve prognosis in patients with ovarian cancer and enlarged lymph nodes.