Background: Preparing family caregivers for a patient's death is an integral component of quality end-of-life care, but temporal changes in emotional preparedness for death and its associations with caregivers' psychological well-being or quality of life (QOL) while providing end-of-life caregiving are under-researched. Our study was conducted to fill this gap. Methods: For this prospective, longitudinal study, the course of changes in adequate emotional preparedness for death and its associations with severe depressive symptoms and QOL were examined on 309 consecutive caregivers of terminally ill cancer patients by univariate and multivariate generalized estimating equation analyses, respectively. Results: Prevalence of adequate emotional preparedness for death was 57.2%, 61.3%, 54.4%, and 46.0% at 181-365, 91-180, 31-90, and 1-30 days before the patient's death, respectively, without significant changes as the patient's death approached. Adequate emotional preparedness for death was associated with caregivers' lower likelihood of severe depressive symptoms (adjusted odds ratio [95% CI]: 0.23 [0.16, 0.32], P < 0.001) but with their better QOL (adjusted β [95% CI]: 7.65 [6.38, 8.92], P < 0.001) in the patient's last year. Conclusions: Without active, effective clinical interventions to promote caregivers' emotional preparedness for death, they cannot automatically become more prepared for the patient's death over time. Adequate emotional preparedness for the patient's death benefits caregivers by its associations with a lower likelihood of depressive symptoms and better QOL. Supportive programs for caregivers of terminally ill cancer patients should focus on not only enhancing caregiving skills but also cultivating emotional preparedness for their relative's death to promote their psychological well-being and QOL.