OBJECTIVE The present study aimed to explore the effects of hyperbaric oxygen therapy on the prognosis and neurological function of patients with severe traumatic brain injury. METHODS A prospective study was carried out in 88 patients diagnosed with severe brain injury at our hospital and they were enrolled as research participants and randomly assigned to control and experimental groups (n = 44 per group) using a random number table method. Both groups underwent routine treatment. Patients in the experimental group were administered hyperbaric oxygen therapy approximately 1 week after admission when their vital signs had stabilized. RESULTS No significant intergroup differences were observed in the Glasgow Coma Scale (GCS) and U.S. National Institutes of Health Stroke Scale (NIHSS) scores before treatment. However, after oxygen treatment, compared with the control group, the experimental group showed higher GCS and lower NIHSS scores. The GCS score at admission, tracheotomy status, and first hyperbaric oxygen therapy duration were independent prognostic factors in patients with severe traumatic brain injury. CONCLUSIONS Hyperbaric oxygen therapy may promote recovery of neurological function and improve the cognitive function and prognosis of patients with severe traumatic brain injury.