Purpose <p>To explore the failure patterns, outcomes, and treatment response of differentiated non-keratinizing nasopharyngeal carcinoma (DNKC) and to further investigate the role of plasma Epstein-Barr virus (EBV)-DNA in follow-up monitoring, prognostic prediction, and assessment of treatment efficacy in DNKC.</p> Methods <p>We retrospectively collected data from patients diagnosed with DNKC from January 2015 to February 2022. The life-table method, Kaplan-Meier survival, and Cox proportional hazards analysis were used for statistical analyses.</p> Results <p>A total of 102 patients were included. Of the 77 patients with available EBV-DNA levels, 61 patients (79.2%) had EBV-DNA detectable before treatment. Twenty-seven patients (26.5%) experienced disease recurrence, and 88.9% (24/27) relapsed in the first three years. There were 20 patients who experienced disease recurrence and had pre-treatment EBV-DNA status records. At the time of disease progression, 4 patients initially had undetectable EBV-DNA remained undetectable. Among the 16 patients with initially detectable EBV-DNA, 15 (93.8%) had detectable EBV-DNA. Nodal stage and EBV-DNA levels before treatment were found to be independent prognostic factors for distant metastasis-free survival (DMFS) and disease-free survival (DFS). Those with residual EBV-DNA after induction chemotherapy had significantly inferior DMFS (<i>P</i> = 0.003), DFS (<i>P</i> = 0.006), and overall survival (OS) (<i>P</i> = 0.006) than those without residual EBV-DNA after IC. Those with residual EBV-DNA after radiotherapy had significantly inferior local recurrence-free survival (<i>P</i> = 0.003), DMFS (<i>P</i> &lt; 0.001), DFS (<i>P</i> &lt; 0.001), OS (<i>P</i> &lt; 0.006) than those without residual EBV-DNA after radiotherapy.</p> Conclusion <p>Our study highlights the aggressive nature of DNKC, characterized by early recurrence. EBV-DNA levels may serve as a biomarker to monitor treatment response, prognostic prediction, and recurrence surveillance.</p>