Background: Advance care planning aims to ensure that care received during serious and chronic illness is consistent with the person’s values, preferences and goals. However, less than 40% of people with dementia undertake advance care planning internationally. Aim: This study aims to describe the perspectives of people with dementia and their carers on advance care planning and end-of-life care. Design: Systematic review and thematic synthesis of qualitative studies. Data sources: Electronic databases were searched from inception to July 2018. Results: From 84 studies involving 389 people with dementia and 1864 carers, five themes were identified: avoiding dehumanising treatment and care (remaining connected, delaying institutionalisation, rejecting the burdens of futile treatment); confronting emotionally difficult conversations (signifying death, unpreparedness to face impending cognitive decline, locked into a pathway); navigating existential tensions (accepting inevitable incapacity and death, fear of being responsible for cause of death, alleviating decisional responsibility); defining personal autonomy (struggling with unknown preferences, depending on carer advocacy, justifying treatments for health deteriorations); and lacking confidence in healthcare settings (distrusting clinicians’ mastery and knowledge, making uninformed choices, deprived of hospice access and support at end of life). Conclusion: People with dementia and their carers felt uncertain in making treatment decisions in the context of advance care planning and end-of-life care. Advance care planning strategies that attend to people’s uncertainty in decision-making may help to empower people with dementia and carers and strengthen person-centred care in this context.