Background: Experiences of end-of-life care and early bereavement during the COVID-19 pandemic are poorly understood. Aim: To identify clinical and demographic risk factors for sub-optimal end-of-life care and pandemic-related challenges prior to death and in early bereavement, to inform clinical practice, policy and bereavement support. Design: Online national survey of adults bereaved in the UK (deaths between 16 March 2020 and 2 January 2021), recruited via media, social media, national associations and organisations. Setting/participants: 711 participants, mean age 49.5 (SD 12.9, range 18–90). 628 (88.6%) were female. Mean age of the deceased was 72.2 (SD 16.1, range miscarriage to 102 years). 311 (43.8%) deaths were from confirmed/suspected COVID-19. Results: Deaths in hospital/care home increased the likelihood of poorer experiences at the end of life; for example, being unable to visit or say goodbye as wanted ( p < 0.001). COVID-19 was also associated with worse experiences before and after death; for example, feeling unsupported by healthcare professionals ( p < 0.001), social isolation/loneliness (OR = 0.439; 95% CI: 0.261–0.739), and limited contact with relatives/friends (OR = 0.465; 95% CI: 0.254–0.852). Expected deaths were associated with a higher likelihood of positive end-of-life care experiences. The deceased being a partner or child also increased the likelihood of positive experiences, however being a bereaved partner strongly increased odds of social isolation/loneliness, for example, OR = 0.092 (95% CI: 0.028–0.297) partner versus distant family member. Conclusions: Four clear risk factors were found for poorer end-of-life care and pandemic-related challenges in bereavement: place, cause and expectedness of death, and relationship to the deceased.