Introduction Family carers of people with dementia are their most important support in practical, personal, and economic terms. Carers are vital to maintaining the quality of life (QOL) of people with dementia. This review aims to identify factors related to the QOL of family carers of people with dementia. Methods Searches on terms including “carers,” “dementia,” “family,” and “quality of life” in research databases. Findings were synthesized inductively, grouping factors associated with carer QOL into themes. Results A total of 909 abstracts were identified. Following screening, lateral searches, and quality appraisal, 41 studies (n = 5539) were included for synthesis. A total of 10 themes were identified: demographics; carer–patient relationship; dementia characteristics; demands of caring; carer health; carer emotional well-being; support received; carer independence; carer self-efficacy; and future. Discussion The quality and level of evidence supporting each theme varied. We need further research on what factors predict carer QOL in dementia and how to measure it.