This study aimed to determine the association between household types and healthy dietary practices among Korean adults. A cross-sectional analysis was performed using nationwide data on 23,488 participants from the 2017-2021 Korea National Health and Nutrition Examination Survey (KNHANES). Based on self-reported data, the participant household types were classified into single- and multi-person households. The adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for healthy dietary practices according to household types were calculated by applying multivariable logistic regression analysis after adjusting for confounders. Of total, 11.21% and 88.79% were single- and multi-person households, respectively. Compared with individuals living in multi-person households, those in single-person households had lower odds of adhering to healthy dietary practices (AOR: 0.88, 95% CI: 0.79-0.98) and consuming adequate saturated fatty acids (<7% of energy) (AOR: 0.78, 95% CI: 0.69-0.88). In addition, men and individuals aged 65 years living in single-person households exhibited lower odds of consuming adequate saturated fatty acids and 500 g of fruit and vegetables per day than those in multi-person households. Single-person households often find it a challenge to practice a healthy diet. Hence, nutritional policies and educational support that help individuals living alone consume healthier diets are warranted.