Sarcopenia has been demonstrated to be adversely correlated with the prognosis of various cancers. Our study aimed to estimate the prognostic value of sarcopenia in conjunction with inflammatory indices [neutrophil-to-lymphocyte ratio (NLR)] for evaluating the prognosis of patients with esophageal squamous cell carcinoma (ESCC) undergoing chemoradiotherapy.This study retrospectively analyzed 255 patients with ESCC who received chemoradiotherapy from January 2012 to December 2018. Multivariate Cox regression analysis was employed to identify prognostic values of assessed factors following a novel prognostic scoring system (SMI-NLR), covering sarcopenia and NLR during different treatment courses.Kaplan-Meier analysis revealed significantly greater overall survival (OS) rates in the nonsarcopenia group than in the sarcopenia group (P = 0.011). The low NLR group (< 4.84) demonstrated significantly higher OS rates than the high NLR group (≥ 4.84) (P < 0.001). The SMI-NLR prognostic model was established through multivariate analysis, revealing that Karnofsky performance status [hazard ratio (HR) = 0.285; 95% confidence interval (CI) = 0.117-0.699; P = 0.006], clinical staging (HR = 5.223; 95% CI = 1.879-14.514; P = 0.002), and preSMI-NLR (HR = 0.544; 95% CI = 0.330-0.898; P = 0.017) were independent factors affecting the prognosis of patients with ESCC. Nomograms were constructed based on these data providing more accurate 1-, 3-, and 5-year survival rates for patients with ESCC.Our study indicates the effectiveness of the combined sarcopenia and NLR prognostic model for the prognostic evaluation of patients with ESCC having undergone chemoradiotherapy.© 2024. The Author(s).