Background And Aims: Invasive fungal infections (IFI) in children with newly diagnosed acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) are poorly characterized, especially in lower-middle income countries (LMICs). This study aims to identify the incidence, risk factors and outcomes of IFI in a pediatric cohort with ALL/LBL. Methods: We retrospectively analysed pediatric patients diagnosed with ALL/LBL between January and December 2023 at a tertiary cancer center in India. Patients were risk-stratified and treated per the modified ICiCLe protocol. IFIs were classified as proven, probable and possible according to the revised EORTC/MSG consensus definition. Results: Among 407 patients, 392 (96%) had ALL. The overall incidence of IFI was 24%, with probable/proven infections in 12%. Mold infections predominated (79 cases, 77%), followed by yeast infections (21 cases, 21%). In comparison to patients without IFIs, those with IFIs were more likely to have received dexamethasone (30% vs 20%; p=0.009) and anthracycline (28% vs 14%; p=0.001) during induction. Chemotherapy interruptions occurred in 56% of IFI cases, impacting treatment continuity. The 6-week mortality rate of patients with IFI was 15%, rising to 26% in probable/proven cases. Coexisting bacterial infection was associated with increased mortality (odds ratio: 19.2[95%CI: 3.5-105]; p=0.001). Conclusion: IFIs are common in newly diagnosed ALL/LBL patients in LMICs, particularly during early phases of therapy. These infections are associated with considerable mortality, often compounded by concomitant bacterial sepsis. Given these findings, consideration of antifungal prophylaxis is warranted to mitigate morbidity and mortality due to IFIs.