Objectives To investigate survival up to early adulthood for children with intellectual disability and compare their risk of mortality with that of children without intellectual disability. Study design This was a retrospective cohort study of all live births in Western Australia between January 1, 1983 and December 31, 2010. Children with an intellectual disability (n = 10 593) were identified from the Western Australian Intellectual Disability Exploring Answers Database. Vital status was determined from linkage to the Western Australian Mortality database. Kaplan-Meier product limit estimates and 95% CIs were computed by level of intellectual disability. Hazard ratios (HRs) and 95% CIs were calculated from Cox proportional hazard regression models adjusting for potential confounders. Results After adjusting for potential confounders, compared with those without intellectual disability, children with intellectual disability had a 6-fold increased risk of mortality at 1-5 years of age (adjusted HR [aHR] = 6.0, 95%CI: 4.8, 7.6), a 12-fold increased risk at 6-10 years of age (aHR = 12.6, 95% CI: 9.0, 17.7) and a 5-fold increased risk at 11-25 years of age (aHR = 4.9, 95% CI: 3.9, 6.1). Children with severe intellectual disability were at even greater risk. No difference in survival was observed for Aboriginal children with intellectual disability compared with non-Aboriginal children with intellectual disability. Conclusions Although children with intellectual disability experience higher mortality at all ages compared with those without intellectual disability, the greatest burden is for those with severe intellectual disability. However, even children with mild to moderate intellectual disability have increased risk of death compared with unaffected children.