Aim: This study aims to assess the influence of training on nurses’ attitudes toward end-of-life care during the COVID-19 pandemic alarm state in Spain. Design: Cross-sectional descriptive study. Data collection was carried out by means of an ad hoc questionnaire using Google Forms in April and May 2020. The score of attitudes toward end-of-life care was used, to which sociodemographic variables and training in palliative care were added. Methods: Data were collected from 238 nursing professionals who had cared for COVID-19 and non-COVID-19 adult patients at the end-of-life stage in a hospital or nursing home. Results: Results showed that 51% of the nurses in the sample had training in palliative care. However, the percentage decreased to 38.5% among those who cared for COVID-19 patients and to 44.5% in those who cared for non-COVID-19 patients. In relation to attitudes about end-of-life care, more positive attitudes and a higher mean score were found in the trained group. Conclusions: Palliative care training is a key element in end-of-life care and is even more important in times of COVID-19. Impact: Although end-of-life accompaniment has been studied, few studies have included the influence of training on this during the pandemic. This study identifies key elements of accompaniment and training in a comparison of COVID-19 and non-COVID-19 patients during the pandemic. In relation to attitudes toward end-of-life care, the results showed a more positive attitude and a higher mean score in the trained group (3.43 ± 0.37 versus 3.21 ± 0.32), the difference being statistically significant (p < 0.001).