This study evaluated the effects of replacing skipped meals with oral nutritional supplements (ONS) on the nutritional status and functional health of older adults. A total of 29 participants aged ≥ 65 years who regularly skipped at least one meal per day were included in this single-arm study. For 8 weeks, participants consumed two packs of ONS daily (150 mL each, providing 400 kcal and 18 g of protein) as a substitute for skipped meals. Nutritional status, nutrient intake, body composition, and physical function were assessed before and after the intervention. The Nutrition Quotient for the Elderly score significantly increased from 58.97 to 63.62 (p = 0.014). Total nutrient intake, including ONS, significantly improved compared with baseline (p < 0.01). Body weight and body mass index increased significantly from 58.87 to 59.47 kg (p = 0.028) and from 23.9 to 24.18 kg/m² (p = 0.016), respectively. Calf circumference decreased significantly from 34.1 to 33.39 cm (p = 0.010). Physical function, assessed using the Short Physical Performance Battery, showed significant improvement (p = 0.003). In conclusion, replacing skipped meals with ONS may enhance nutritional status and support functional health in older adults.