Background: Deaths by COVID-19 have left behind nearly 12 million recent bereaved individuals worldwide and researchers have raised concerns that the circumstances of COVID-19 related deaths will lead to a rise prevalence of prolonged grief disorder (PGD) cases. However, to date, no studies have examined the prevalence of PGD among people bereaved due to COVID-19. This study aimed to estimate the prevalence of PGD and investigated demographic and loss-related factors associated with prolonged grief symptoms among Chinese individuals bereaved due to COVID-19.Methods: This was a cross-sectional online survey conducted between September 1 and October 3, 2020. A total of 422 Chinese participants (55.5% males; 32.73 [9.31] years old) who lost a close person due to COVID-19 participated in the study. Demographic and loss-related information was collected, and self-reported prolonged grief symptoms were measured by a 13-item International Prolonged Grief Disorder Scale (IPGDS: 1–65) and a 17-item Traumatic Grief Inventory Self Report (TGI-SR: 1–85). Multiple linear regression analysis was used to determine the associated factors of levels of grief symptoms.Results: Prevalence of PGD was 37.8% screened by IPGDS and 39.9% by TGI-SR. No difference was found in levels of grief symptoms between participants whose close one died more than 6 months ago and those who experienced the loss less than 6 months ago. More severe prolonged grief symptoms was associated with losing a close person by COVID-19 rather than complications (B: 5.284; 95% CI: 0.521–10.047), losing a partner (B: 6.645; 95% CI: 2.547–10.743), child (B: 6.013; 95% CI: 0.128–11.899), parent (B: 5.554; 95% CI: 1.679–9.429), grandparent (B: 4.894; 95% CI: 0.690–0.097), feeling more traumatic about the loss (B: 1.574; 95% CI: 0.413–2.735), being closer to the deceased (B: 1.610; 95% CI: 0.368–2.851), and having more conflicts with the deceased (B: 0.743; 95% CI: -0.040–1.527).Conclusions: Echoing to researchers’ concerns, prevalence of PGD is high among people bereaved due to COVID-19. Individuals with higher risk of developing PGD should be identified and bereavement support should be offered as early as possible.