This study was conducted to identify the nutrition literacy levels of Korean adults and the associated influencing factors. A total of 770 adults aged 19–64 years participated in online surveys and individual interviews conducted according to age groups from May to October 2021. The results of the evaluation of the nutrition literacy levels showed that the average correct answer rate among the participants was 78.7%. Nutrition literacy levels were found to be high in females, lower age groups, metropolis residents, those with high monthly incomes, and those with a bachelor’s degree or higher. Multiple regression analysis showed that males, higher age groups, and rural area residents had a negative correlation with nutrition literacy compared with that of females, lower age groups, and metropolis residents. A more positive correlation was observed in those with higher monthly incomes and educational degrees. In the future, experts should monitor whether the nutritional information transmitted through various forms of media is correct or incorrect, and specific measures should be taken to enhance nutrition literacy to promote the health and nutrition management of Korean adults.