Purpose: As society rapidly ages, the number of older single-person households continues to grow. These individuals often face barriers to healthcare access due to limited social and family support, which increases their risk of experiencing unmet medical needs. This study aims to investigate the prevalence of unmet medical care among single-person elderly households and to examine the influence of demographic, health-related, and community environmental factors, thereby providing evidence to inform policies aimed at improving healthcare accessibility. Methods: This study analyzed data from the 2023 Korean Elderly Survey, including 3,423 individuals aged 65 years or older from older single-person households. Unmet medical care was defined as a self-perceived need for treatment that was not fulfilled. A complex sample logistic regression analysis was conducted to identify associated factors. Results: Significant risk factors for unmet medical care included low educational attainment, unemployment, low income, weak social networks, and poor relationships with children. In addition, frailty, negative self-rated health, multiple chronic conditions, depression, cognitive decline, inadequate nutrition, and insufficient physical activity were associated with higher risks. Environmental factors such as difficulty going out and long distances to healthcare facilities further increased the likelihood of unmet medical needs. Conclusion: Older single-person households face multiple vulnerabilities — including economic hardship, poor health, limited social support, and environmental barriers — that contribute to unmet medical needs. Addressing this issue requires comprehensive policy interventions that enhance community-based care, improve healthcare accessibility, and strengthen social connections.