Objective: Little is known about the impact of acquired brain injury (ABI) on the long-term quality-of-life (QoL) in children and youth. The objectives of this study were to illustrate the long-term QoL trajectories at 5 years post-ABI. Methods: The QoL of children between 5-18 years (n = 94) admitted to McMaster Children’s Hospital with ABI were assessed longitudinally for a minimum of 5 years post-injury using the Child Health Questionnaire. Independent t-tests were used to examine differences in QoL between the study cohort and a normative sample at different time points. Mixed-effects models were used to identify predictors for QoL. Results: The QoL of children with ABI was significantly poorer (p < 0.05) than the normative data on all domains and at all-time points except at baseline. The CHQ physical summary score (PHSS) showed a significant decline immediately after injury and a significant recovery at 8 months post-injury; while the CHQ psychosocial summary score (PSSS) showed a significant immediate decline, which remained over the course of the study. Pre-morbid school record, time post-injury and mechanism of injury significantly predicted the CHQ PSSS. Conclusions: QoL is impacted by ABI regardless of severity. This impact is further affected by time post-injury.