Background: While acute kidney injury (AKI) is frequent in severe SARS-CoV2-related pneumonia ICU patients, few data are still available about its risk factors. Methods: Retrospective observational study performed in four university affiliated hospitals in Paris. AKI was defined according to the KIDGO guidelines. Factors associated with AKI were picked up using multivariable mixed-effects logistic regression. Independent risk factors of day 28 mortality were assessed using Cox model. Results: 379 patients (median age 62 [53,69], 77% of male) were included. Half of the patients had AKI (n = 195, 52%) including 58 patients (15%) with AKI stage 1, 44 patients (12%) with AKI stage 2, and 93 patients (25% with AKI stage 3). Chronic kidney disease (OR 7.41; 95% CI 2.98-18.4), need for invasive mechanical ventilation at day 1 (OR 4.83; 95% CI 2.26-10.3), need for vasopressors at day 1 (OR 2.1; 95% CI 1.05-4.21) were associated with increased risk of AKI. Day 28 mortality in the cohort was 26.4% and was higher in patients with AKI (37.4 vs. 14.7%, P < 0.001). Neither AKI (HR 1.35; 95% CI 0.78-2.32) nor AKI stage were associated with mortality (HR [95% CI] for stage 1, 2 and 3 when compared to no AKI of, respectively, 1.02 [0.49-2.10], 1.73 [0.81-3.68] and 1.42 [0.78-2.58]). Conclusion: In this large cohort of SARS-CoV2-related pneumonia patients admitted to the ICU, AKI was frequent, mostly driven by preexisting chronic kidney disease and life sustaining therapies, with unclear adjusted relationship with day 28 outcome.