BACKGROUND: This study aimed to identify the impact of illness uncertainty on physical and mental health-related quality of life (HRQoL) in patients with unruptured intracranial aneurysms (UIAs) after coil embolization. METHODS: A cross-sectional study was conducted and HRQoL was evaluated using the Short Form-12 Health Survey Questionnaire, which assesses physical and mental HRQoL. RESULTS: The participants had a mean age of 56.4 years, and among them, 190 (71.2%) were women. Physical and mental HRQoL were negatively correlated with physical symptoms, anxiety, depression, and illness uncertainty. Mental HRQoL was positively correlated with social support. Physical HRQoL was significantly influenced by depression (β = −0.26, P = .004) and was not influenced by illness uncertainty (β = −0.10, P = .101). Mental HRQoL was significantly influenced by anxiety (β = −0.45, P < .001), depression (β = −0.19, P = .003), social support (β = 0.14, P = .004), and illness uncertainty (β = −0.14, P = .005). The finding that illness uncertainty influences HRQoL suggests a basis for interventions aimed at improving mental HRQoL by reducing illness uncertainty in patients with UIAs. CONCLUSION: The physical and mental HRQoL in patients with UIAs after coil embolization is negatively influenced by depression, whereas mental HRQoL is also affected by anxiety, illness uncertainty, and social support. These results may serve as reference data for the design and development of interventions to improve HRQoL in patients with UIAs after coil embolization.