Introduction: Neurogenic heterotopic ossification (NHO) occurs as a complication of traumatic brain injury (TBI). Management of clinically significant NHO remains variable. Complications of mature NHO include limitation of mobility. The effect of the extracorporeal shock wave therapy (ESWT) on range of motion at hip and knee, and function in patients with TBI with chronic NHO was investigated. Methods: A series of single-case studies applying ESWT to chronic NHO at the hip or knee of 11 patients with TBI were undertaken at a rehabilitation hospital. Participants received four applications of high-energy EWST delivered to the affected hip or knee over a period of 8 weeks. Two-weekly follow- up assessments were carried out; final assessments were made 3 and 6 months post-intervention. Range of motion (ROM) and Functional Reach (FR) or Modified Functional Reach (MFR) were measured. Results: Application of high-energy ESWT was associated with significant improvement in ROM (flexion) of the NHO-affected knee (Tau = 0.833, 95% CI 0.391–1.276, p = 0.002) and significant improvement of FR (Overall Tau 0.486, 95% CI 0.141–0.832, p = 0.006); no significant improvement in hip ROM or MFR. Conclusions: ESWT may improve mobility and balance of patients with TBI who have chronic NHO.