The objective of this study was to describe the incidence of impaired cerebral autoregulation and to describe the relationship between impaired cerebral autoregulation and outcome after severe pediatric traumatic brain injury (TBI). We prospectively examined cerebral autoregulation in 28 children ≤17 (10 ± 5) years with a Glasgow coma scale score <9 within the first 72 h of pediatric intensive care unit admission. Children with isolated focal TBI were excluded. Glasgow outcome scores (GOS) were collected at hospital discharge, as well as 3 and 6 months after severe TBI. GOS <4 reflected poor outcome. Cerebral autoregulation was impaired in 12/28 children. An autoregulatory index <0.4 was associated with GOS <4 at 6 months (p = 0.005). Impaired cerebral autoregulation, early after severe pediatric TBI, was associated with a poor 6-month outcome.