Background: Informal carers of people with dementia report having unmet needs for support and few supportive interventions have been shown to be effective. There is a need to develop needs assessment instruments and supportive interventions with a holistic and person-centred approach to meet the various and complex needs of carers. The aim of this study was to provide an overview of carers’ support needs when caring for people with dementia with the objectives to map and synthesise knowledge on key concepts of carers’ support needs. Methods: A scoping review methodology was used. A literature search was conducted in PsycINFO, CINAHL, PubMed and EMBASE between January 2007 and October 2019. Three authors independently selected articles meeting the inclusion criteria, and data were extracted using a matrix developed for that purpose. Inductive content analysis was used to synthesise key concepts of carers’ support needs. Results: The search identified 2748 articles after removing duplicates, and 122 articles were included in the mapping of carers’ support needs. Synthesising carers’ support needs indicated that the full extent of support needs emerges in the interaction between the carer and the person cared for and that it is possible to categorise support needs into four key concepts related to: 1) the carer as a person, 2) managing being a carer, 3) providing care, and 4) knowledge of dementia. Conclusion: The findings of this study help to map a framework describing carers’ support needs that may guide the development of future needs assessment instruments and supportive interventions.