There has been limited research conducted on the quality of life (QoL) of children with intellectual disabilities (IDs). We investigated the QoL in children aged 5-18 years with ID and compared the results with healthy children of the same age in this study. The results indicated that the scores of students with ID were lower on all scales and also that children with ID should be supported in all QoL dimensions (physical, social, emotional, and school functioning). Associations between QoL and factors such as the educational level of the mothers, income level of the family, age at diagnosis, age group, and level of ID were examined in the ID group. A diagnosis of ID before the age of 2 was found to have a statistically significant positive effect on QoL scores. Our findings highlight that early diagnosis is the most important measure to improve the QoL of people with ID.