This retrospective cohort study was to assess the prognostic value of preoperative geriatric nutritional risk index (GNRI) on survival outcomes for patients with locally advanced oral squamous cell carcinoma (LAOSCC). Patients with LAOSCC receiving upfront radical surgery at a single institute from January 2007 to February 2017 were enrolled. The primary outcomes in the study were 5-year overall survival (OS) and cancer-specific survival (CSS) rates, and a nomogram based on GNRI and other clinical-pathological factors was established for individualized OS prediction. There were 343 patients enrolled in this study. The optimal cut-off value of GNRI was observed to be 97.8. Patients in the high-GNRI group (GNRI ≥97.8) had statistically significantly better outcomes in 5-year OS (74.7% vs. 57.2%, p = 0.001) and CSS (82.2% vs. 68.9%, p = 0.005) when compared with the low-GNRI group (GNRI <97.8). In Cox models, low GNRI remained an independent negative prognosticator of OS (HR: 1.6; 95% CI: 1.124–2.277; p = 0.009) and CSS (HR: 1.907; 95% CI: 1.219–2.984; p = 0.005). The c-index of the proposed nomogram, incorporating assorted clinicopathological factors and GNRI, had a statistically significant increase compared with the predictive nomogram constructed by the TNM staging system alone (0.692 vs. 0.637, p < 0.001).” Preoperative GNRI is an independent prognostic factor of OS and CSS in patients with LAOSCC. A multivariate nomogram that includes GNRI may better help us to accurately estimate individual survival outcomes.