Purpose: This study evaluates activities of daily living activities, health status, and nutritional-related characteristics of older adults living alone by age. Methods: This study analyzed data from aged 65 or older who participated in the National Survey of Living Conditions and Welfare. Data were collected on the following factors: demographic characteristics, comorbidities, body mass index (BMI), need for assistance with activities of daily living, exercise, subjective health status, Mini-Mental State Examination for Dementia Screening (MMSE-DS), and short form of Geriatric Depression Scale (SGDS-K). The definition of malnutrition is BMI <18.5 kg/m2 . Results: A total of 3,136 participants were included, with 1,488 classified as younger older adults and 1,648 classified as older older adults. The prevalence of hypertension, difficulties in daily living, need for daily living assistance, MMSE-DS, and SGDS-K scores were significantly higher in the older older adults than in the younger older adults. Both groups had low levels of participation in education and use of community centers or welfare centers. The distribution of cognitive function decline and depression was high in the malnourished group. Furthermore, the malnourished group without cognitive decline or depression had higher monthly income, exercise performance, and use of electronic device. Conclusion: Older adults who live alone suffer from poor health behaviors, activities of daily living, and nutritional status, and the older adults are even more vulnerable. Therefore, monitoring of older adults living alone with poor living conditions is necessary, and intensive efforts are needed to improve their health and functional status.