Background <p>Immune-inflammatory and nutritional status are recognized as influencing factors for survival in older patients with nasopharyngeal carcinoma (NPC). This study explores the relationships between age, immune-inflammatory and nutritional status and survival outcomes, and the potential mediating effect in this association.</p> Methods <p>We analyzed 977 non-metastatic NPC patients aged ≥ 60 years between January 2015 and December 2022. Overall survival (OS) and cancer-specific survival (CSS) served as the primary endpoints. Mediation analyses were performed to assess the effects of age and immune-inflammatory and nutritional status on the prognosis. Restricted cubic spline curves were employed to investigate non-linear associations. Kaplan-Meier analysis was used to analyze the survival endpoints.</p> Results <p>Age independently predicted poorer survival, with platelet-to-lymphocyte ratio (PLR), prognostic nutritional index (PNI) and serum albumin (ALB) emerging as significant prognostic factors in older NPC patients. Mediation analysis revealed that the indirect effects of age on OS through PLR, PNI, and ALB were 0.01%, 3.7%, and 6.2%, respectively, and the indirect effects on CSS were − 0.01%, 6.7%, and 7.7%, respectively. Among them, ALB values significantly mediated the effects of age on OS and CSS (both P_indir &lt; 0.01), persisting after multivariable adjustment. Patients with ALB values ≥ 41.3 g/L exhibited superior 5-year OS (77.5% vs. 66.7%, P &lt; 0.001) and CSS (80.6% vs. 71.3%, P &lt; 0.001), with subgroup analyses confirming robustness.</p> Conclusions <p>Immune-inflammatory and nutritional status mediate age-dependent survival disparities in older NPC patients. These findings underscore the clinical imperative of addressing inflammatory burden and nutritional depletion in geriatric oncology and advocate for integrated biomarker-guided management strategies.</p>