The study investigated the effect of social relationships on vulnerability among community‐dwelling older adults living alone in Taiwan. Data were extracted from the de‐identified service records of 2116 older adults living alone. Logistic regression models were used to identify the connection between social relationships and vulnerability. The results demonstrated that close social relationships help reduce vulnerability for older adults living alone. Moreover, the data indicated a statistically significant relationship between frailty and vulnerability and a statistically significant relationship between public assistance and vulnerability. An increase in the degree of frailty increases the risk of exposure to threats for older adults living alone. However, public assistance benefits older adults living alone. Existing policy and social work interventions aim to strengthen social safety nets for older adults living alone and establish social networks for older adults living alone through an institutional approach to prevent exposure to threats. Moreover, policymakers should focus not only on risk factors (e.g., frailty) but also on protective factors (e.g., social relationships and public assistance).