Background Lymph node ratio (LNR), defined as the ratio of positive lymph nodes to the total nodes harvested, has emerged as a potential prognostic marker in oral tongue squamous cell carcinoma (OTSCC). This study aimed to evaluate the prognostic significance of LNR in patients with OTSCC and its association with overall survival (OS), disease-free survival (DFS), and pathological features. Methods A retrospective cohort study was conducted, including 127 patients with biopsy-proven OTSCC treated between 2008 and 2023. LNR was calculated and stratified into two groups using a cutoff value of 0.01 determined by receiver operating characteristic (ROC) analysis. Survival outcomes were assessed using Kaplan–Meier analysis and Cox regression models. Results The median LNR was 0.01 (n = 59 for LNR < 0.01; n = 68 for LNR ≥ 0.01), and ROC analysis identified 0.01 as the optimal cutoff (AUC = 0.748). Patients with LNR ≥ 0.01 demonstrated significantly worse 5-year OS (43.3%) compared to those with LNR < 0.01 (84.9%) (p = 0.001). Similarly, DFS was significantly reduced in the high-LNR group. Median OS for the cohort was 177 months. On multivariate analysis, LNR ≥ 0.01 was independently associated with increased mortality risk (HR: 4.51; 95% CI 1.91–10.6; p = 0.001). Elevated LNR was also significantly associated with adverse pathological features, including perineural invasion, lymphovascular space invasion, positive surgical margins, recurrence, and distant metastasis. Conclusion LNR is significantly associated with survival outcomes in patients with OTSCC. A low cutoff value (0.01) effectively stratifies patients into distinct risk groups and may provide improved prognostic insight beyond traditional nodal staging. Incorporation of LNR into clinical practice may enhance risk stratification and guide postoperative management.