Background: Acute kidney injury (AKI) poses a significant morbidity and mortality risk to critically ill COVID-19 patients. The aim of this study was to investigate the incidence, predictors, and outcomes of AKI in patients admitted to the intensive care unit with critically ill COVID-19 pneumonia.Methods: A multicenter retrospective study in Saudi Arabia of adult patients aged at least 18 years diagnosed with COVID-19 pneumonia and admitted to the intensive care unit between May 2020 and May 2021. The occurrence of acute kidney injury and associated risk factors, the need for continuous renal replacement therapy, and the outcome were reported.Results: The study included 340 patients admitted to the ICU with COVID-19. Their mean age was 66.7±13.4 years, ranging from 49 to 84 years, and most of them were men (63.8%). The most common concomitant diseases were hypertension (71.5%), diabetes (62.4%), IHD (37.6%), CKD (20%), heart failure (19.4%), and 81.2% suffered from ARDS. AKI occurred in 60.3% of patients, 38% were stage 1, 16.6% were stage 2, and 45.4% were stage 3. Approximately 39% of patients required continuous renal replacement therapy (CRRT), of which 76.2% were stage 3, which was significantly higher than the other stages (p<0.001). AKI patients suffered significantly from asthma and had lower levels of C-reactive protein (CRP), ferritin, lactate dehydrogenase (LDH), and blood urea nitrogen (BUN) and higher creatinine levels than patients without AKI (p<0.05 all). The overall mortality rate was 39.4%, and the mortality rate was significantly higher in patients with AKI than in patients without AKI (48.3% versus 25.9%; p<0.001).Conclusion: AKI is common in adults admitted to the intensive care unit with COVID-19 and is associated with an increased risk of death. Early detection of AKI and appropriate treatment can positively impact COVID-19 the outcome. CRRT is the preferred dialysis method in critically ill ICU patients with AKI.