Abstract Background and Aims To date, delirium is considered one of the most frequent neuropsychiatric acute syndromes among hospitalized populations. In general medicine, the risk factors for delirium are well-established but there are limited data concerning the incidence and predictors of delirium in nephrological patients. The aims of the study were (i) to assess the prevalence and the risk factors for delirium in hospitalized patients with acute kidney injury (AKI) and chronic kidney disease (CKD), and (ii) to evaluate the effect of delirium on in-hospital mortality. Method A cohort of 942 patients admitted to the Nephrology Department of a tertiary-care Hospital from January 2023 to December 2023 were enrolled in a prospective observational study. Delirium was diagnosed by a psychiatrist during the hospitalization. The endpoint was defined as hospital death or hospital discharge. Relevant sociodemographic, nephrological- and medical-related clusters were assessed with logistic uni- and multivariable regression methods to evaluate their association with delirium and in-hospital mortality. A two-tailed value <0.05 was considered significant. Results In the studied group, mean age was 62.85 years, 519 (55.09%) patients being males. The prevalence of delirium was 5.41% (51/942 patients). The delirious patients were older (mean 70.04 vs. 62.44 years; P<0.001) and with a longer duration of hospitalization (13.12 ± 7.90 days vs. 10.76 ± 8.92 days; P=0.007). Univariable regression analysis showed that delirium was associated with age (r=0.117, P<0.001), alcohol abuse (r=0.144, P<0.001), history of stroke (r=0.184, P<0.001), vascular dementia (r=0.125, P<0.001), dehydration (r=0.175, P<0.001), sepsis (r=0.144, P<0.001), and acute kidney injury (AKI) stage 2 and 3 (r=0.155, P<0.001). In multivariable regression analysis, the independent predictors of delirium were: age (adjusted odds ratio (OR) 1.029, 95% confidence interval (CI): 1.002–1.056, P=0.034), alcohol abuse (OR=4.728, 95% CI: 1.968-11.359, P=0.001), history of stroke (OR=3.493, 95% CI: 1.849-6.598, P<0.001), and AKI stage 2 and 3 (OR=2.175, 95% CI: 1.152-4.105, P=0.017). Chronic kidney disease was not associated with a higher risk of delirium (OR=0.583, 95% CI: 0.308-1.110, P=0.097). Delirium was associated with increased in-hospital mortality (47.05% vs. no-delirium 14.36%, P<0.001) and was an independent predictor of in-hospital mortality (OR=3.074, 95% CI: 1.630-5.797, P=0.001). Conclusion In this study conducted on patients hospitalized in a nephrology ward age, alcohol abuse, history of stroke, and AKI stage 2 and 3 were independent risk factors for delirium. Delirium significantly increased in-hospital mortality. The findings of the study emphasize the strong connectivity between AKI and acute brain dysfunction.