Caregiving and bereavement outcomes are strongly influenced by socio-cultural context. Past research has found higher levels of caregiver burden and psychological morbidity in Portuguese compared to Brazilian caregivers. This study compared Brazilian and Portuguese family caregivers in palliative care to identify differences in psychological morbidity and caregiver burden and their relationship with psychosocial factors such as sociodemographic variables, circumstances of end-of-life care and dying, social support, family functioning, and perception of quality of care. Prospective data were collected from convenience samples of family caregivers in Brazil (T0 n = 60; T1 n = 35) and Portugal (T0 n = 75; T1 n = 29) at two separate time points—during caregiving (T0), and during the first two months of bereavement (T1). The study samples consisted mostly of women, offspring, and spouses. In both countries, family caregivers devoted most of their day to taking care of their sick relatives and reported a lack of practical support. Portuguese caregivers had higher levels of burden than Brazilian caregivers, and in both populations a greater burden was associated with more psychopathological symptoms. Higher caregiver burden among Portuguese caregivers was associated with the circumstances of death and the perceived lack of emotional support. Among Portuguese caregivers, symptomatology persisted during bereavement, reaching significantly higher levels of anxiety, somatization, and peritraumatic symptoms compared to the Brazilian sample. These results show differences between family caregiver samples in Portugal and Brazil during the bereavement process. Understanding the underlying cultural patterns and mechanisms requires future research.