Background Hospital‐acquired acute kidney injury (AKI) in humans and dogs increases morbidity and nonsurvival. Azotemia at presentation has been associated with a poor outcome in horses; however, prevalence and consequences of hospital‐acquired AKI are unreported. Hypothesis/Objectives To evaluate the prevalence of AKI in hospitalized horses, risk factors associated with AKI, and the effect of AKI on short‐term survival. We hypothesized that the prevalence of AKI in horses is similar to that reported in other domestic mammalian species and would be associated with nonsurvival. Animals Adult horses hospitalized for >2 days from which a minimum of 2 measurements of serum creatinine concentration were available. Methods Retrospective cohort study. Clinical records were reviewed and horses grouped according to their baseline serum creatinine concentration and change in serum creatinine concentration from baseline. The associations between signalment, diagnosis, and treatment variables, and the presence of azotemia or AKI were assessed using multinomial logistic regression. The relationship between these conditions and survival to discharge was evaluated. Results Three hundred twenty‐five horses were included; 4.3% (14/325) had azotemia at baseline and 14.8% (48/325) developed AKI. There were no significant associations between investigated risk factors and development of AKI. The presence of azotemia and AKI did not significantly affect survival to discharge (P = .08 and .81, respectively). Conclusions and Clinical Importance The prevalence of AKI in this population of hospitalized horses is similar to that reported in dogs and humans; however, in this study population, there was less impact on morbidity and short‐term survival.