Background Acute leukaemia represents a crucial health challenge. However, nationwide data delineating the incidence of acute leukaemia subtypes, as well as mortality and survival outcomes, remain scarce in China. We aimed to provide a comprehensive assessment of the epidemiology of acute leukaemia subtypes across China. Methods We conducted a population-based cancer registry analysis and cohort study in China, by integrating data from five national databases through unique national identification numbers. The main outcomes were age-standardised rates (ASRs) for incidence and mortality and overall survival for acute leukaemia subtypes. Acute leukaemia incidence and mortality data in 2019 were extracted from National Cancer Centre (NCC) registries linked to the Hospital Quality Monitoring System (HQMS), stratified by age, sex, and region. ASRs were calculated with Segi's world standard population with 95% CIs across the general population. For the survival analysis, we established a cohort from the Chinese Childhood Leukaemia Registry (33 530 children aged 0-14 years) and National Adult Acute Leukaemia Registry of China (71 477 adults aged >= 15 years) for 2016-20, integrated with the Cause of Death Reporting System and HQMS. Patients were stratified by subtype, age, sex, region, molecular characteristics, treatment modalities, and diagnosis period (2016-18 vs 2019-20). Overall survival and cause-specific survival were assessed with the Kaplan-Meier method at multiple timepoints (1 month, and year 1 to year 5) in our cohort. Multivariate Cox regression analysis was performed to identify prognostic factors. Findings Based on NCC registries covering a population of 628<middle dot>4 million, we estimated 43 275 new acute leukaemia cases and 27 049 deaths in 2019 in China, with an ASR for incidence 2<middle dot>83 (95% CI 2<middle dot>78-2<middle dot>88) per 100 000 population and an ASR for mortality of 1<middle dot>51 (1<middle dot>48-1<middle dot>54) per 100 000 population. The ASR for the incidence of non-acute promyelocytic leukaemia-acute myeloid leukaemia was 1<middle dot>24 (95% CI 1<middle dot>21-1<middle dot>26) per 100 000 population, that of acute lymphoblastic leukaemia was 0<middle dot>92 (0<middle dot>89-0<middle dot>95) per 100 000 population, and that of acute promyelocytic leukaemia was 0<middle dot>22 (0<middle dot>21-0<middle dot>23) per 100 000 population. The incidence of acute leukaemia spiked in children aged 1-4 years (4<middle dot>54 per 100 000), then declined, and then rose markedly after age 60 years, peaking at 9<middle dot>33 per 100 000 in people aged 75-79 years, before declining, while overall mortality remained relatively low across younger age groups (0-44 years), then increased progressively with advancing age, from 1<middle dot>23 per 100 000 in adults aged 45-49 years to 8<middle dot>77 per 100 000 in those aged 80-84 years. In children, 5-year overall survival was 66<middle dot>5% (95% CI 65<middle dot>3-67<middle dot>9) for non-acute promyelocytic leukaemia acute myeloid leukaemia, 91<middle dot>1% (89<middle dot>6-92<middle dot>6) for acute promyelocytic leukaemia, and 85<middle dot>4% (84<middle dot>9-85<middle dot>8) for acute lymphoblastic leukaemia; in adults, 5-year overall survival was 23<middle dot>9% (23<middle dot>4-24<middle dot>3) for non-acute promyelocytic leukaemia acute myeloid leukaemia, 82<middle dot>5% (81<middle dot>7-83<middle dot>4) for acute promyelocytic leukaemia, and 30<middle dot>1% (29<middle dot>2-30<middle dot>9) for acute lymphoblastic leukaemia. Survival improved in the more recent period (2019-20 vs 2016-18: hazard ratio 0<middle dot>97 [95% CI 0<middle dot>95-0<middle dot>99]; p=0<middle dot>0014), particularly among younger adults with non-acute promyelocytic leukaemia acute myeloid leukaemia (aged <60 years) and acute lymphoblastic leukaemia (aged <40 years), with improvements primarily attributable to expanded application of allogeneic haematopoietic stem-cell transplantation. However, prognosis remained poor in patients with acute leukaemia aged 60 years and older (5-year overall survival 14<middle dot>9% [95% CI 14<middle dot>3-15<middle dot>5] in patients aged 60-74 years, and 4<middle dot>8% [4<middle dot>2-5<middle dot>4] in patients aged >= 75 years). Interpretation This comprehensive nationwide study of acute leukaemia incidence, mortality and survival outcomes across China establishes age-specific epidemiological benchmarks, enabling ongoing risk factor monitoring, while supporting expanded transplantation access for eligible patients and highlighting the urgent need for novel, less toxic therapies for older patients who bear a disproportionately higher disease burden. Funding State Key Laboratory of Medical Genomics, Double First-Class Project, Overseas Expertise Introduction Project for Discipline Innovation, National Natural Science Foundation of China, Innovative Research Team of Highlevel Local Universities in Shanghai, Shanghai Guangci Translational Medical Research Development Foundation, and CAMS Innovation Fund for Medical Sciences. Copyright (c) 2025 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.