Introduction: Paediatric acute leukaemias(PAL) are the commonest haematological malignancy noted in South-East Asia(SEA), with 70-85% being acute lymphoblastic leukaemia (ALL). Studies from Asian populations demonstrate lymphoid predominance, predominantly between 5–10 years. Published data in Sri Lanka is limited. Objective: To evaluate haematological, morphological and immunophenotypic characteristics of PAL diagnosed between 2021 - 2025 and compare with SEA data. Methods: A retrospective descriptive cross-sectional study conducted on patients ≤15 years diagnosed with acute leukaemia. Full blood count (FBC) was performed on BC Mindray 6800 Plus automated analyzer. Morphological assessment done on Leishman-stained blood and bone marrow aspirate smears. Flow cytometry performed using BD FACSCanto™ II analyzer. Results: Of 73 PAL cases, B-ALL was 80.8% while AML and T-ALL were 9.6% each. Mean age at diagnosis was 7 .6 ± 3.9 years with male predominance. Marked leukocytosis was prominent with a mean white blood cell count of 58.6 ± 46.2 ×10? /L with a maximum of 182 ×10? /L.Anaemia and thrombocytopenia were consistent across all subtypes. Bone marrow examination demonstrated diffuse blast infiltration. Flow cytometry confirmed B-ALL cases with CD19 and cyCD79a expression and CD34 positivity . The proportion of B-ALL observed in this cohort was comparable with reported SEA populations. Conclusion: PAL in this cohort demonstrated subtype distribution comparable with SEA, but presented with marked leukocytosis and other cytopenias, indicating advanced disease. This underscores the need for early diagnosis. Cytogenetics is essential for risk stratification in PAL at diagnosis, but is a considerable limitation in our limited resource setting.