BACKGROUND: Peripheral vascular malformations (VMs) may lead to disfigurement of the body and face, potentially impairing aesthetic appearance. Yet, data on appearance in this population is limited. This study aimed to examine appearance-related concerns and their impact on health-related quality of life (HR-QoL) in patients with VMs. METHODS: In this cross-sectional study, 384 adults and 194 children with VMs were invited to complete the Outcome Measures for VAscular MAlformations (OVAMA) questionnaire to evaluate potential appearance-related concerns on a five-point verbal-rating scale, with higher scores indicating more appearance-related concerns (e.g., colour-difference, facial-distortion, reduced self-esteem, and dissatisfaction with appearance). HR-QoL was evaluated using Patient-Reported Outcome Measurement Information System (PROMIS). Subgroups of patients reporting more appearance-related concerns were identified using univariate analysis. Associations between appearance-related concerns and various HR-QoL domains (e.g., anxiety and social participation) were assessed. RESULTS: A total of 184 patients (32%) completed the questionnaires; 121 patients (66%) reported that one or more appearance outcome was severely affected (i.e., 4-5 out of 5). The following factors statistically significant associated with more appearance-related concerns: capillary/combined origin, facial localization, subcutaneous tissue involvement, larger size, overgrowth, and diagnosis of a syndrome. In adults, dissatisfaction with appearance and reduced self-esteem due to the appearance of the VM correlated with more anxiety and depression symptoms. Reduced self-esteem correlated with less social participation. In children, bodily distortion and being stared at were correlated with less peer relationships. CONCLUSION: Severe appearance-related concerns were present in two-thirds of patients with VMs, impairing their mental HR-QoL. Clinicians should acknowledge appearance-related aspects, monitor psychological well-being, and offer intervention aimed at improving satisfaction with appearance.