Inflammatory markers in the blood have been linked to tumor prognosis, but their specific prognostic significance in nasopharyngeal carcinoma (NPC) patients undergoing intensity-modulated radiotherapy (IMRT) is not well established. This study aims to evaluate the prognostic value of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) in this patient population. A total of 406 non-metastatic NPC patients were included in the study. NLR, PLR, and LMR were stratified according to their average values. The Kaplan-Meier method was used to estimate progression-free survival (PFS) and overall survival (OS). Cox multivariate regression analysis was performed to evaluate the associations of NLR, PLR, and LMR with PFS and OS. Patients with NLR > 2.78had worse PFS (P = 0.008) and OS (P < 0.001); PLR > 162.48 was related to lower PFS (P = 0.018) but not OS (P = 0.29); LMR > 5.05 showed no significant difference in PFS and OS compared to LMR ≤ 5.05 (P values were 0.13 and 0.94, respectively). Multivariate analysis indicated that NLR was an independent prognostic factor for PFS (HR, 1.674; 95% CI, 1.006-2.784; P = 0.047) and OS (HR, 4.143; 95% CI, 2.111-8.129; P = 0.000), while PLR and LMR did not demonstrate significant associations with PFS and OS. This study identifies NLR as a novel and independent prognostic indicator for NPC patients receiving IMRT, offering valuable insights that could inform future clinical decision-making. In contrast, PLR and LMR did not demonstrate significant prognostic value in this context.