BACKGROUND: To investigate potential predictive factors and assess the utility of systemic inflammatory and nutritional indexes as prognostic indicators for survival in patients with FIGO stage III-IVA squamous cervical cancer (squamous HR-LACC) treated with concurrent chemoradiotherapy. METHODS: We included consecutive patients with PET-CT diagnosed squamous HR-LACC undergoing curative chemoradiotherapy from November 2016 to April 2024. We systematically reviewed data pertaining to pretreatment clinicopathologic characteristics, hematological parameters, and treatment specifics. A range of composite inflammatory and nutritional indices were calculated, including the neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, lymphocyte-to-monocyte ratio, systemic immune-inflammation index, systemic inflammation response index, pan-immune-inflammation value, and prognostic nutritional index (PNI). X-Tile software was utilized to establish optimal cut-off values based on progression-free survival (PFS). Both univariate and multivariate Cox regression analyses were conducted to identify factors associated with PFS and overall survival (OS). RESULTS: Among 157 patients (median age 55) included, 136 had lymph node involvement, and 45 had para-aortic metastasis. After a median follow-up of 35 months, 47 patients had disease progression, and 22 died, yielding 3-year PFS and OS rates of 66.2% and 82.0%, respectively. Multivariate analysis revealed that low SCC-Ag (HR: 1.518, 95% CI: 1.067-2.159, p = 0.020), para-aortic lymph node involvement (HR: 1.864, 95% CI: 1.020-3.408, p = 0.043), and low PNI (HR: 1.477, 95% CI: 1.105-1.975, p = 0.009) were independently associated with worse PFS, whereas low PNI emerged as the sole independent risk factor for diminished OS (HR = 1.525, 95% CI: 1.002-2.323, p = 0.049). CONCLUSIONS: PNI, a readily obtainable metric based on albumin and lymphocyte count, can serve as a predictor of survival in HR-LACC patients undergoing concurrent chemoradiotherapy. Further research is necessary to ascertain whether optimizing pretreatment nutritional status, a modifiable factor, can enhance outcomes in these high-risk patients.