Aims: Although oral tongue squamous cell carcinoma (OTSCC) with pathological depth of invasion (pDOI) ≤3 mm is generally considered low risk, late cervical lymph node metastasis can still occur. We aimed to develop a simple clinicopathological risk stratification model incorporating tumor budding (TB) and pDOI to identify patients at increased risk of delayed neck recurrence. Methodology: We retrospectively analyzed 107 patients with pT1–T2N0 OTSCC who underwent primary resection and had confirmed pDOI ≤3 mm. TB was evaluated on hematoxylin and eosin–stained sections. Patients were classified into three groups: low risk (pDOI <2 mm and TB <5), intermediate risk (either pDOI ≥2 mm or TB ≥5), and high risk (pDOI ≥2 mm and TB ≥5). The primary endpoint was late cervical lymph node metastasis within 3 years. Recurrence rates were compared among groups, and survival analyses were performed. Results: Neck recurrence occurred in 9 patients (8.4%). Recurrence rates differed substantially among groups: 1.4% (1/71) in the low-risk group, 11.1% (3/27) in the intermediate-risk group, and 55.6% (5/9) in the high-risk group. In the Cox proportional hazards model, both the intermediate- and low-risk groups showed significantly better regional recurrence-free survival (RRFS) than the high-risk group (intermediate: HR 0.15, 95% CI 0.04–0.62, p = 0.009; low: HR 0.02, 95% CI 0.002–0.16, p < 0.001). Conclusion: Even in OTSCC with shallow invasion (≤3 mm), a subset of patients remains at substantial risk of late cervical metastasis. A simple model combining TB and pDOI may help identify biologically aggressive tumors and support individualized postoperative surveillance and neck management.