Oral squamous cell carcinoma (OSCC) is the sixth most common type of cancer globally. While smoking is a key risk factor, rising cases in non-smokers highlight the need to explore other factors like diet. This scoping review aims to deepen the evidence on the relationship between OSCC and diet, following PRISMA-ScR guidelines, and was registered on Open Science Framework. Searches were performed in four electronic databases: MEDLINE, Embase, Web of Science, and Lilacs, without date or language restrictions. Studies were evaluated, extracted, and compiled in a narrative table. Seventeen studies with 10,954 patients were analyzed. Most patients were male (74.63%), aged 18–89 (average 50.62). Studies were mainly from high (82%) and medium (17%) Human Development Index (HDI) countries. Dietary surveys included a Food Frequency Questionnaire (FFQ) (58.8%), interviews/questionnaires (17.6%), and an FFQ with a photographic atlas (5.9%). Certain foods in excess like fruits, vegetables, and tea were inversely associated with OSCC, while salty meats, dairy, coffee, sausages, and fried and spicy foods were positively associated. Due to the heterogeneity of the tools used to obtain food frequency data, the results should be interpreted cautiously. New standardized studies and randomized trials are essential to advance understanding and control confounding factors in this field.