Purpose: The word ‘diet’ usually encompasses the consumption of food that includes all the necessary nutrients required for the optimal functioning of the body. Nutritional supplements hold a supreme position due to the demanding lifestyles or medical conditions in this current era. Although medical literature has sufficient evidence exploring the effect of nutrients on general health, this systematic review aimed at specifically evaluating the role of nutritional supplements on oral health in adults. Methods: PRISMA guidelines were followed in conducting this systematic review where four electronic databases including Scopus, PubMed, EMBASE, and Web of Science were reviewed. Based on the inclusion criteria, four studies exploring the effect of oral nutritional supplements on oral health among the adult population were included in this systematic review. Results: This review generated evidence suggesting a positive effect of nutritional supplements on oral health. These findings were depicted in the form of a reduction in plaque scores, probing depths, gingival inflammation, and greater improvement in periodontal healing among individuals with higher intakes of nutritional supplements within recommended doses. Conclusions: The systematic review outlines the positive impact of consuming nutritional supplements in the recommended dosage on oral health. Additionally, this review stresses the necessity for interventional studies to further investigate the effects of nutritional supplements on oral health, particularly in regard to periodontal healing. PROSPERO registration: CRD42021287797 (27/11/2021).