Objective: Family caregivers are often intensively involved in palliative and end-of-life cancer care. A variety of interventions to support family caregivers have been developed, differing in target population, modality, and components. We aimed to systematically examine characteristics and the effectiveness of interventions to support family caregivers of patients with advanced cancer. Methods: A systematic review was conducted using Embase, Medline Ovid, Web of Science, Cochrane, Google Scholar, and Cinahl. This review included quantitative studies published from January 2004 until January 2020 reporting on interventions to support family caregivers of patients with advanced cancer in all care settings. Results: Out of 7957 titles, 32 studies were included. Twenty-two studies were randomized controlled trials. Interventions were delivered to four target populations: individual family caregivers (n = 15), family caregiver-patient dyads (n = 11), families (n = 2) and peer groups (n = 4). Most interventions (n = 26) were delivered face-to-face or by phone, two were delivered online. Most interventions included multiple components and were primarily aimed at supporting family caregivers' self-care. Twenty-nine interventions were shown to have beneficial effects on family caregiver outcomes, mostly in the psycho-emotional (n = 24), daily functioning (n = 13) and social dimension (n = 6). Individual interventions were mainly effective in the psycho-emotional dimension, dyad and family interventions in the psycho-emotional and social domain, and group interventions mainly had an effect on daily functioning. Conclusions: Interventions to support family caregivers in advanced cancer care vary widely. Most intervention studies reported beneficial effects for the wellbeing of family caregivers. There is evidence that the target group is associated with beneficial effects on different outcome dimensions.