Individualized aerobic exercise treatment prescribed within 10 days of injury facilitates recovery in adolescents after sport-related concussion (SRC) and reduces incidence of persisting post-concussive symptoms (PPCSs) beyond 4 weeks. The effect of aerobic exercise treatment on quality of life symptoms is, however, unknown. This planned secondary aim of a published randomized controlled trial found that while adolescents prescribed aerobic exercise recovered faster, there was no difference on the Pediatric Quality of Life (PedsQL) questionnaire scores during the 4-week intervention period. Nevertheless, adolescents who experienced PPCS reported significantly worse initial visit (within 10 days of injury) symptoms on the PedsQL than those who recovered within 4 weeks. Higher scores on the PedsQL correlated with greater initial visit concussion symptom burden and more abnormalities on a concussion-relevant visio-vestibular examination. Thus, the PedsQL captures the clinical severity of concussion and is prognostic of risk for delayed recovery when administered early after SRC in adolescents.