This study aims to determine the relationship between chewing ability and the nutritional status of the elderly in Korea. This study utilized the data from the Korea National Health and Nutrition Examination Survey (KNHANES) conducted from 2013–2018 for persons who were ≥65 years of age. Of the 7835 subjects, 43.2% had chewing difficulty. Compared to the normal group, the chewing difficulty group had more stress, lower exercise frequency, less snack intake, a lower frequency of eating out, and a higher proportion of food insecurity. The chewing difficulty group had significantly lower food intake compared to the normal group, including various food groups such as cereals and grain, potatoes, fruits, meat, and milks and dairy products. The intake of fresh fruits was 24.5% lower and the intake of plant food (fresh fruits and nonstarchy vegetables) was 17.8% lower in the chewing difficulty group compared to the normal group. In addition, the intake of most nutrients (carbohydrates, fat, calcium, phosphorus, sodium, potassium, vitamin A, riboflavin, niacin, and vitamin C) was significantly lower in the chewing difficulty group than in the normal group. The chewing difficulty was significantly associated with undernutrition (OR = 1.63). In conclusion, chewing ability is closely related to food and nutrient intake among the elderly, which can decrease the quantity and quality of diet and is also related to undernutrition. Therefore, it is necessary to develop customized nutrition programs and aging-friendly food products that consider the chewing ability of the elderly.