Acute kidney injury (AKI) is a common complication in cancer patients, but the data are lacking in Asian countries. We aimed to assed the epidemiology, correlated risk factors and outcomes of AKI in cancer patients from China. We conducted a nationwide cohort study of cancer patients who were admitted to 25 general and children hospitals across China from January 1, 2013 to December 31, 2015. We obtained patient-level data from the electronic hospitalization information system and laboratory databases of all inpatients who had at least two serum creatinine tests within any 7-day window during their first 30 days of hospitalization. AKI was defined and staged according to Kidney Disease Improving Global Outcomes criteria. Incidence rate and risk factor profiles for AKI were examined. Outcomes of interest included in-hospital mortality, length of stay and daily costs. A total of 136,756 adult cancer patients were assessed in our study. The overall incidence of AKI was 7.5%, of which 1.6% were community acquired and 5.9% hospital acquired. The top three cancer types with high incidence of AKI were bladder cancer, leukemia, and lymphoma. Risk factors for community-acquired and hospital-acquired AKI were similar, including age, increased baseline serum creatinine, shock and urinary tract obstruction. In-hospital death occurred in 12.0% with AKI vs. 0.9% cancer patients without AKI. After adjustment for confounders, the severe AKI was associated with higher risk of in-hospital death, prolonged length of stay and higher daily costs. Clinicians should increase their awareness of AKI in hospitalized cancer patients. © 2018 UICC