To explore the prognostic factors in patients with advanced olfactory neuroblastoma (ONB) underwent endoscopic surgery. Retrospective medical records were reviewed of patients with pathologically proven ONB who underwent endoscopic surgical resection. Clinicopathological characteristics including patient demographics, treatment, complications, follow-up, and outcomes were analyzed. Kaplan-Meier overall survival (OS) and disease-free survival (DFS) curves were plotted. Univariate and multivariate Cox regression models were used to determine prognostic factors. Eighty-five patients with Kadish stage C ONB were examined. According to the various staging systems used, most patients harbored modified Kadish stage C (78.8%). Twenty-six patients (30.6%) underwent bony skull base resection, 11 (12.9%) underwent dura resection, and 24 (28.2%) underwent additional intracranial resection that included the olfactory bulb and duct. Median follow-up was 39 months. Five-year OS and DFS rates were 83.7% and 74.9%, respectively. Five-year OS was 100% in patients treated with bony skull base resection and 77.5% in those who were not (P = .052). Dura resection did not improve OS. Multivariate Cox regression analysis identified perioperative complications (P = .009), gross total resection (P = .004), orbital invasion (P = .014), postoperative radiotherapy (P = .030), and bony skull base resection (P = .019) as independent prognostic predictors. For patients with advanced ONB, endoscopic surgery in conjunction with radiotherapy and chemotherapy is effective and safe. Dura resection should be performed with caution in selected patients to balance survival and complications. Postoperative radiotherapy is important to improve OS and DFS.