Background: Long-term conditions are common in people living with dementia; their self-management is an important determinant of wellbeing. Family carers often support or substitute self-care activities, and act as proxies for self-management, as dementia progresses. Objectives: To conduct the first systematic review of how management of long-term conditions in people with dementia is best enabled and supported, including factors that facilitate or inhibit self-management and management by a proxy. Design: Systematic review. Data Sources We systematically searched MEDLINE, PsychINFO, Embase and Allied and Complementary Medicine databases up to November 2018. Review methods We identified the long-term conditions most prevalent in people with dementia that require an element of self-management. We then developed our inclusion criteria to identify qualitative and quantitative studies describing the self-management (or self-management assisted by family carers) of long-term conditions in people with dementia. Two authors independently rated study validity using a standardised checklist. We synthesised qualitative and quantitative findings using a data driven convergent synthesis approach. Results: We included 12 articles meeting predetermined inclusion criteria: seven qualitative, two case studies, two quantitative and one mixed methods study. We identified four main themes across these studies: (1) dementia symptoms impeding treatment regimens (forgetfulness, decreased understanding, ability to communicate symptoms and behavioural and psychological symptoms); (2) adapting routines to be simpler, (using memory aids and accommodating physical limitations); (3) negotiating self-management support (carer availability and knowledge; balancing needs for safety and empowerment); and (4) interface with professionals, (Routine simplification, condition specific education, and acknowledging carer role). Conclusions: People living with dementia can be supported to manage their own health for as long as possible, through simplifying routines and reminding, but where this can no longer be negotiated, carers take over responsibility for self-management, often due to safety concerns. Empowerment of people with dementia to remain involved in their care reduces the loss experienced by this transition. Communication and partnership between clinicians and carers is critical when supporting people living with a long-term condition and dementia. Care planning for people living with dementia and a long-term condition should include explicit discussion of how these partnerships will work and guidance on strategies carers can use to support people to self-manage long-term conditions.