ObjectiveThe demanding nature of caregiving and limited social support can lead to informal carers experiencing loneliness, which can impact their well-being and overall health service use (HSU). The study aims to examine the association between loneliness with HSU and Health state utility values among informal carers in Australia. MethodsData were derived from three waves (2009, 2013, and 2017) of the nationally representative longitudinal Household Income and Labour Dynamics of Australia (HILDA) survey, focusing on adult informal carers. Outcome measures included visits to the General Practitioner, the number of hospital admissions, and the SF-6D score. Generalized Estimating Equations (GEE) analysis was conducted to explore the associations between loneliness and HSU, as well as loneliness and utility values (based on SF-6D) while adjusting for age, sex, education, marital status, income, and physical/mental health conditions. ResultsAfter controlling for covariates, lonely carers reported lower utility values (IRR = 0.91, 95%CI [0.89, 0.93], p < 0.001) compared to non-lonely carers. Lonely carers reported a higher number of GP visits (IRR = 1.18, 95% CI [1.04, 1.36], p < 0.05) as well as a higher likelihood of visiting specialists (AOR = 1.31, p = 0.046) and hospital doctors (AOR = 1.42, p = 0.013) compared to the non-lonely carers. ConclusionsThe findings of this study highlight the relationship between loneliness on both healthcare utilization and carers’ overall well-being. Addressing loneliness through targeted interventions and social support systems can help improve health outcomes and potentially reduce the overall healthcare costs among informal carers in Australia.