Abstract Background Caregiving can be associated with several adverse health impacts, such as in terms of mental health, health services use, or health-related quality of life (HRQoL). This study assessed HRQoL levels in Portuguese Informal Caregivers, and their relationship with caregiver psychosocial characteristics (e.g., perceived general and mental health; perceived level of support) and caregiving circumstances (e.g., caregiving duration, caregiving hours). Methods A cross-sectional study was conducted through an online survey directed to informal caregivers. HRQoL was measured using the Portuguese translation of the EQ-5D-5L. This instrument yields two values for HRQoL: a health profile (EQvalue) covering five dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression), and a visual analogue scale (EQvas). Bivariate analyses were performed and results with p-values below 0.05 were considered statistically significant. Results A total of 760 informal caregivers were surveyed (mean age 57 years (±9.9), 92.5% female, 41.5% at least university level, 44.4% works full or part-time). The mean total score for EQvalue (n = 733) was 0.8 (SD = 0.2). The mean total score for EQvas (n = 760) was 63.1 (SD = 21.5). The perceived general (p < 0.001) and mental (p < 0.001) health status, and the perceived access to healthcare (p < 0.001) were associated with EQvalue score. Also, EQvalue score was found to be directly correlated with the perceived level of support (r = 0.142; p < 0.001) and competence (r = 0,237; p < 0.001), and inversely correlated with the number of caregiving hours per day (r= -0,150; p = < 0,001) and the caregiving duration (r= -0,109; p = 0.008). Conclusions A significant relationship between caregiver HRQoL and several caregiver psychosocial variables was identified. Investing in and promoting the use of respite care services, as well as ensuring better access to healthcare for caregivers, appears important for improving caregivers’ HRQoL. Key messages • Improving caregivers’ access to healthcare and education or training programs (promoting a greater sense of competence) can be important in helping them maintain their quality of life. • Increasing the availability and promoting the use of respite care services by caregivers can be important in helping them maintain their quality of life.