Background: Vietnam has experienced a rapid increase in cancer incidence with many cancers (70%) being diagnosed at a late stage. The majority of physical and psychosocial care is provided by caregivers with minimal professional input. Due to limited resources in hospitals and social and cultural norms regarding caregiving in Vietnam, caregivers provide a range of supportive functions for family members diagnosed with cancer. Objectives: This study sought to provide empirical evidence on the self-identified unmet needs of caregivers of inpatients in national oncology hospitals in Vietnam. Methods: Focus groups and in-depth interviews were conducted with caregivers (n = 20) and health care providers (n = 22) in national oncology hospitals in Hanoi and Ho Chi Minh City. Data was collaboratively analysed using thematic analysis. Findings were validated through key stakeholder group discussions with both caregivers and healthcare providers across multiple regions in Vietnam. Results: Analysis demonstrated that the burden of informal care is high with many caregivers managing patient’s severe and complex health needs with minimal support. Caregivers highlighted four main areas of critical need: (i) challenges in providing long term care, particularly in hospital and in-patient settings, such as accessing comfortable facilities, accommodation and finance; (ii) information needs about cancer, treatment, and nutrition; (iii) support for the emotional impact of cancer; and (iv) training about how to provide care to their family members during treatment and recovery phases. Conclusions: Caregivers provide invaluable support in supporting people with a cancer diagnosis, particularly given wider systemic challenges in delivering cancer services in Vietnam. Increasing visibility and formal support is likely to have both a positive impact upon the health and wellbeing of caregivers, as well as for cancer patients under their care. Given its absence, it is critical that comprehensive psychosocial care is developed for caregivers in Vietnam.