Solid organ transplant recipients (SOTRs) have a heightened risk of adverse coronavirus disease 2019 (COVID-19) outcomes because of immunosuppression and medical comorbidity. We quantified the burden of COVID-19 mortality in United States (US) SOTRs. A sample of deaths documented in the US solid organ transplant registry from June 2020 through December 2022 was linked to the National Death Index to identify COVID-19 deaths and weighted to represent all SOTR deaths during the study period. Among 505 757 SOTRs, 57 575 deaths occurred, and based on the linkage, 12 396 (21.5%) were due to COVID-19. COVID-19 mortality was higher in males (mortality rate ratio [MRR]: 1.13), SOTRs aged 65 years and older (MRR: 1.50 in ages 65-74 vs ages 55-64 years), and non-Hispanic Black and Hispanic SOTRs (MRRs: 1.55 and 1.79 vs non-Hispanic White SOTRs). Kidney and lung recipients had the highest COVID-19 mortality, followed by heart, and then liver recipients. COVID-19 mortality also varied over time and across US states. Overall, SOTRs had a 7-fold increased risk of COVID-19 death compared to the US general population. SOTRs comprised 0.13% of the US population but accounted for 1.46% of all US COVID-19 deaths. SOTRs experience greatly elevated COVID-19 mortality. Clinicians should continue to prioritize COVID-19 prevention and treatment in this high-risk population.