BACKGROUND: Armed conflict has significant impacts on individuals and families living in conflict-affected settings globally. Scholars working to prevent violence within families have hypothesised that experiencing armed conflict leads to an increase in family violence and mental health problems. In this review, we assessed the prevalence of family violence in conflict settings, its association with the mental health of survivors, moderating factors, and the importance of gender relations. METHODS: Following PRISMA guidelines, we systematically reviewed quantitative and qualitative studies that assessed the prevalence of family violence and the association between family violence and mental health problems, within conflict settings (PROSPERO reference CRD42018114443). RESULTS: We identified 2605 records, from which 174 full text articles were screened. Twenty-nine studies that reported family violence during or up to 10 years after conflict were eligible for inclusion. Twenty one studies were quantitative, measuring prevalence and association between family violence and mental health problems. The studies were generally of high quality and all reported high prevalence of violence. The prevalence of violence against women was mostly in the range of 30-40%, the highest reported prevalence of physical abuse being 78.9% in Bosnia and Herzegovina. For violence against children, over three-quarters had ever experienced violence, the highest prevalence being 95.6% in Sri Lanka. Associations were found with a number of mental health problems, particularly post-traumatic stress disorder. The risk varied in different locations. Eight qualitative studies showed how men's experience of conflict, including financial stresses, contributes to their perpetration of family violence. CONCLUSIONS: Family violence was common in conflict settings and was associated with mental health outcomes, but the studies were too heterogenous to determine whether prevalence or risk was greater than in non-conflict settings. The review highlights an urgent need for more robust data on perpetrators, forms of family violence, and mental health outcomes in conflict-affected settings in order to help understand the magnitude of the problem and identify potential solutions to address it.