Objectives Carer burden in dementia is associated with poor outcomes, including early nursing home placement for people with dementia and psychological distress for their carers. Carers of people with young‐onset dementia (YOD) are particularly vulnerable to carer burden. Yet they are often overlooked by clinicians as dementia services are generally designed for older people. We sought to estimate the rate of burden and psychological distress in carers of YOD at a state‐wide tertiary service based in Australia. Methods We conducted a cross‐sectional study examining 71 dyads from a Neuropsychiatry service. We collected patient demographic and clinical data including the Neuropsychiatry Unit Cognitive Assessment tool (NUCOG) and Mini‐Mental State Examination (MMSE). Carer data, such as demographics and psychological distress, were obtained using Depression Anxiety Stress Scale 21 (DASS‐21). Carer burden was rated using the Zarit Burden Inventory‐short version (ZBI). Results Higher carer burden, measured using ZBI, was associated with longer duration of dementia and greater severity of overall cognitive impairment. Carers who felt burdened reported higher levels of stress, depression, and anxiety measured using DASS‐21. Multiple linear regression analysis found carer burden was independently predicted by duration of dementia, total cognition score and carers experiencing psychological stress. Discussion We found that patient variables of dementia duration and cognitive impairment and carer variable of carer stress to be associated with carer burden. Poor executive function was associated with carer stress. Early identification and management of carer burden and psychological distress is important for outcomes. Ideally, this should be provided by a specialist YOD service. Key points In an Australian tertiary neuropsychiatric service, almost a half of informal carers of young‐onset dementia reported feeling significantly burdened. Furthermore, over a third of the carers felt depressed, anxious, or stressed. Higher carer burden was associated with longer duration of dementia and greater severity of overall cognitive impairment. Early identification and management of carer burden and psychological distress is important to achieve better outcomes for both the patient and carer.