Abstract Background Dementia is a leading cause of death in developed nations. Despite an often distressing and symptom laden end of life, there are systematic barriers to accessing palliative care in older people dying of dementia. Evidence exists that 70% of people living with severe dementia attend an emergency department (ED) in their last year of life. The aim of this trial is to test whether a Carer End of Life Planning Intervention (CELPI), co-designed by consumers, clinicians and content specialists, improves access to end of life care for older people with severe dementia, using an ED visit as a catalyst for recognising unmet needs and specialist palliative care referral where indicated. Methods A randomised controlled trial (RCT) enrolling at six EDs across three states in Australia will be conducted, enrolling four hundred and forty dyads comprising a person with severe dementia aged ≥ 65 years, and their primary carer. Participants will be randomly allocated to CELPI or the control group. CELPI incorporates a structured carer needs assessment and referral to specialist palliative care services where indicated by patient symptom burden and needs assessment. The primary outcome measure is death of the person with dementia in the carer-nominated preferred location. Secondary outcomes include carer reported quality of life of the person dying of dementia, hospital bed day occupancy in the last 12 months of life, and carer stress. An economic evaluation from the perspective of a health funder will be conducted. Discussion CELPI seeks to support carers and provide optimal end of life care for the person dying of dementia. This trial will provide high level evidence as to the clinical and cost effectiveness of this intervention. Trial registration ACTRN12622000611729 registered 22/04/2022.