This study aimed to explore the prevalence of and risk factors for self-neglect among older adults who live alone. Data were obtained through face-to-face interview responses of 1,023 older adults living alone in a metropolitan area in South Korea, selected via stratified random sampling, which considered the population variables gender, age group, and district. Descriptive statistics were used to characterize the prevalence of self-neglect, and hierarchical multiple regression analysis was conducted to identify significant risk factors of self-neglect. At least 22.8% of the participants could be considered to have one form of elder self-neglect. Consistent with previous research, self-neglect was more prevalent in the older people living alone who had higher levels of depressive symptoms or a lack of family social support. Unexpectedly, self-neglect was more prevalent among respondents with higher levels of education and cognitive abilities, lower levels of medical comorbidities, and more children. Additionally, social networks of friends and use of social services (formal social support) did not affect the frequency of self-neglect. The findings have implications for gerontological practice and policy, especially for older people living alone in South Korea.