Background: Family caregivers play an integral role in supporting patient self-management, yet how they perform this role is unclear. We conducted a qualitative metasynthesis of family caregivers' processes to support patient self-management of chronic, life-limiting illness and factors affecting their support. Methods: Methods included a systematic literature search, quality appraisal of articles, data abstraction, and data synthesis to produce novel themes. Results: Thirty articles met inclusion criteria, representing 935 international family caregivers aged 18 to 89 years caring for patients with various health conditions. Three themes characterized family caregivers' processes to support patient self-management: "Focusing on the Patient's Illness Needs," "Activating Resources to Support Oneself as the Family Caregiver," and "Supporting a Patient Living with a Chronic, Life-Limiting Illness." Factors affecting family caregivers' support included Personal Characteristics, Health Status, Resources, Environmental Characteristics, and the Health Care System. Conclusions: The family caregiver role in supporting patient self-management is multidimensional, encompassing three processes of care and influenced by multiple factors.