Background: The risk of superinfections and associations with mortality among patients with corona virus disease 2019 (COVID-19) receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) is poorly elucidated. Method: We identified all patients with COVID-19 treated with VV-ECMO >24 h at Rigshospitalet, Denmark from March 2020 to December 2021. Data were obtained by review of medical files. Associations between superinfections and mortality were assessed by logistic regression analyses adjusted for sex and age. Results: Fifty patients, median age 53 years (interquartile range [IQR] 45–59), 66% male, were included. Median time on VV-ECMO was 14.5 days (IQR 6.3–23.5), 42% were discharged from hospital alive. Bacteremia, ventilator associated pneumonia (VAP), invasive candidiasis, pulmonary aspergillosis, herpes simplex virus, and cytomegalovirus (CMV) were detected in 38%, 42%, 12%, 12%, 14%, and 20% of patients, respectively. No patients with pulmonary aspergillosis survived. CMV was associated with increased risk of death, odds ratio 12.6 (95% confidence interval 1.9–257, p =.05), whereas we found no associations between other superinfections and risk of death. Conclusion: Bacteremia and VAP are common but does not seem to affect mortality, whereas pulmonary aspergillosis and CMV are associated with poor prognosis among COVID-19 patients treated with VV-ECMO.