Around 51 million children globally are exposed to elevated levels of arsenic in drinking water However; the extent to which exposure is related to deaths from cancer at a young age is unknown. We assembled a cohort of 58,406 children aged 5–18 years from Health and Demographic Surveillance System of icddrb in Bangladesh and followed during 2003–2015. The follow-up period was 543415 person-years. We observed a significant association between childhood cancer mortality and arsenic exposure in the highest exposure tertile (HR=2.70, 95% CI =1·25–5.83). Arsenic exposure was associated with substantial increased risk of deaths at young age from cancers where child (5–11 years) had a higher risk of death compared to adolescent (12–18 years).