Laryngeal squamous cell carcinoma (LSCC) is a frequent cancer subtype among head and neck cancers. Exacerbated inflammation and nutritional deficit are common features in this type of cancer and can be used as a prognostic marker. This study aimed to investigate the relationship between body mass index (BMI), neutrophil-to-lymphocyte ratio (NLR), and systemic inflammation response index (SIRI) on overall survival (OS) of LSCC patients. In this retrospective cohort study, 168 patients were followed for 5 years. Data on clinical factors, patients' life habits, height, weight, and hematological parameters were collected. BMI, NLR, and SIRI were calculated. Pretreatment NLR≥ 2.02 and SIRI≥ 1160.85 were independent prognostic factors for poor OS. Low BMI did not significantly affect the OS. However, the inflammatory parameters had their predictive capacity altered when stratified by the BMI classification. NLR≥ 2.02 + Low BMI or SIRI≥ 1160.85 + Low BMI increased in 8.6 and 3.8 times the risk of death, respectively. In contrast, stratification by normal/high BMI classification eliminated the predictive capacity of NLR and SIRI. Here, we demonstrated the possible ability of BMI to change the prognostic capacity of inflammatory markers NLR and SIRI in patients with LSCC.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1952447.