Introduction: Acute kidney injury (AKI) has been associated with adverse outcomes among hospitalized patients with Covid-19. Although pre-pandemic data of patients with AKI has shown that volume overload is significantly associated with mortality and need for Renal Replacement Therapy (RRT), the association with worst outcomes among patients with AKI and Covid-19 has not been studied. Thus, the purpose of the study was to evaluate the effect of fluid overload in AKI with progression of the disease and mortality among patients hospitalized with Covid-19. Methods Observational retrospective cohort study that included volume balances, clinical and biochemical data of 412 hospitalized patients with Covid-19 and AKI. Univariate and Cox regression analyses were used to evaluate the association of fluid overload with 28-day mortality, AKI stage 3 and RRT. Results The mean age of the subjects was 55 ± 15 years, 64.1% were women, 69.7% developed AKI at any stage, 47.2% had diabetes, 31.4% had hypertension, and only 4.5% had chronic kidney disease. Likewise, the 28-day mortality was 20.4%, 43.3% patients required mechanical ventilation, 22.3% developed AKI stage 3, and 9.5% needed RRT. The median of global fluid overload was 1441cc (-489 to 3736), and 59.7% had a global fluid overload of > 1000 cc at discharge. After Cox regression analysis the risk for 28-day mortality, AKI stage 3 and RRT was HR = 3.014 (1.573–5.777), 3.159 (1.708–5.840), and 3.607 (1.128–11.539), respectively (p < 0.05 for all). Conclusion In the setting of AKI, fluid volume overload was associated with worst outcomes among hospitalized patients with Covid-19.