BACKGROUND: Acute kidney injury (AKI) can be a severe complication in cancer patients. However, uncertainty remains regarding the risk of and prognosis after AKI following cancer treatments. We therefore aimed to examine the risk of and mortality after AKI following a wide range of specific cancer treatments, including surgical procedures, anticancer drugs, and hematopoietic stem cell transplantations (HSCTs). METHODS: We conducted a nationwide population-based cohort study. We included adult patients receiving cancer treatment in Denmark from 2010 to 2024. We calculated the risk of AKI within 7 days after surgeries, 1 year after initiation of anticancer drugs, and 100 days after HSCTs. Furthermore, we examined the 1-year mortality in patients with and without AKI following cancer treatment. RESULTS: We identified 357,870 cancer patients. The 7-day risk of AKI after surgery ranged from 0.3% (breast cancer surgery) to 68.9% (radical nephrectomy in kidney cancer) while the 1-year risk following anticancer drug treatment ranged from 3.5% (cyclophosphamide in breast cancer) to 79.3% (all drugs in acute lymphatic leukemia). The 100-day AKI risk following HSCT ranged from 20.7% (multiple myeloma) to 81.8% (leukemia). For most treatments, AKI was associated with a higher 1-year hazard ratio and risk of death, with exceptions including radical nephrectomy in kidney cancer. CONCLUSION: In conclusion, several cancer treatments were associated with a high risk of AKI, and AKI was associated with increased mortality in most treatments. These findings highlight the prognostic value of assessing kidney function following specific cancer treatments in clinical practice.