Objective: In the developing brain cortical thickness follows age-dependent changes which may be disrupted in the presence of brain injury. The current investigation examined cortical thickness in relation to the development of post-concussive symptoms in a pediatric sample of children who sustained a mild traumatic brain injury (mTBI) or orthopedic injury (OI). Method: Research participants were 163 male and female children ranging in age from 7 to 15 who sustained either mTBI (n = 106) or OI (n = 57). All underwent brain imaging with the same 3-Tesla scanner and protocol with quantitative imaging based on a volume acquisition T1-weighted sequence using FreeSurfer 5.3. A post-concussive symptom inventory (PCSI) was completed by both the injured child and parent acutely and at 6 months post-injury. Results: The expected age-dependent reductions in cortical thickness were observed in both the mTBI and OI groups, which did not differ after correction for multiple-comparisons. However, when cortical thickness was examined by combining mTBI and OI subjects into a single group, even after controlling for age and sex, reduced cortical thickness was associated with increased PCSI scores, particularly notable in the region of the left fusiform gyrus and right insular cortex. Conclusion: Since post-concussive symptoms are not injury specific both children with mTBI and OI had elevated PCSI scores, which interestingly related to reduced insular cortex and fusiform thickness. In that these regions are involved in processing and perception of pain, cortical thickness reductions may reflect pre-existing vulnerability within these regions for processing interoceptive stimuli that emerge following injury, regardless of mechanism of injury.