Background/Objectives: To assess the pretreatment and posttreatment clinical factors associated with the rate of survival at 1, 3, and 5 years in stage IV nasopharyngeal carcinoma (NPC) patients. Methods: Clinicopathological characteristics of 61 Stage IV NPC patients diagnosed between 2008 and 2022 in a single tertiary medical center were retrospectively reviewed. Univariate and multivariate analyses were performed to evaluate the prognostic factors associated with overall survival (OS), disease-specific survival (DSS), and disease-free survival (DFS). A nomogram was developed to forecast DSS. Results: The OS at 1-year, 3-year, and 5-year were 93%, 70%, and 57%, while the DSS at 1-year, 3-year, and 5-year were 93%, 73%, and 58%, whereas the DFS at 1-year, 3-year, and 5-year were 51%, 44%, and 41%, respectively. In multivariate analyses, posttreatment body mass index (BMI) < 21.6 kg/m² (hazard ratio [HR] 2.717, 95% confidence interval [CI] 1.248–5.917, p = 0.012) was an independent indicator for worsened OS. Posttreatment BMI < 21.6 kg/m² (HR 3.003, 95% CI 1.340–6.757, p = 0.008) and pretreatment systemic inflammation response index (SIRI) ≥ 125 (HR 2.841, 95% CI 1.256–6.429, p = 0.012) were independent indicators for worsened DSS. Posttreatment BMI < 21.6 kg/m² (HR 3.650, 95% CI 1.757–7.576, p = 0.001), change in BMI < −1.93 kg/m² (HR 3.731, 95% CI 1.642–8.475, p = 0.002), and pretreatment SIRI ≥ 125 (HR 3.541, 95% CI 1.717–7.304, p = 0.001) were independent indicators for worsened DFS. A nomogram was created to predict DSS using posttreatment BMI and pretreatment SIRI. Conclusions: Associations with survival were observed between posttreatment BMI and OS, DSS, and DFS; pretreatment SIRI and DSS/DFS; and changes in BMI and DFS among patients with stage IV NPC. The developed nomogram aids in survival prediction.