Background: Patients in palliative care are usually conceptualised as recipients of support from family caregivers. Family caregivers in palliative care are typically defined as providers of support to patients. Little is known about reciprocal dimensions of support provision between patients and family caregivers in palliative care. Aim: To identify processes of mutual support between patients and family caregivers in palliative care and factors that contribute to or obstruct mutual support between patients and family caregivers in palliative care. Design: Systematic review and narrative synthesis of original peer-reviewed research published between January 2000 and March 2020. Data sources: Medline, CINAHL, Embase, AMED, PsycINFO and PsycARTICLES. Results: After full-text screening, 10 studies were included. We identified that patients and family caregivers in palliative care can support one another by mutually acknowledging the challenges they face, by remaining positive for one another and by jointly adapting to their changing roles. However, patients and family caregivers may not routinely communicate their distress to each other or reciprocate in distress disclosure. A lack of mutual disclosure pertaining to distress can result in conflict between patients and family caregivers. Conclusions: Few studies have focused in whole or in part, on reciprocal dimensions of support provision between patients with advancing non-curable conditions, and their family caregivers in palliative care. Further research is required to identify key domains of mutual support between patients and family caregivers in palliative care.