Background: The prevalence of traumatic brain injury (TBI) in prison populations has been found to vary considerably. This study aimed to determine the prevalence of TBI in a prison population in New Zealand and to identify whether age, ethnicity, offence type, security classification and sentence length were linked to TBI prevalence. Methods: All offenders admitted to a new Corrections Facility over a 6-month period (May-November 2015) were screened to understand their history of TBI. Data was merged with demographic information, details of the offence type, sentence length and security classification from the prison database. Binary logistic regression was used to identify the contribution of predictors on TBI history. Results: Of the 1,061 eligible male prisoners, 1,054 (99.3%) completed a TBI history screen. Out of the 672 (63.7%) who had sustained at least one TBI in their lifetime, 343 (32.5%) had experienced multiple injuries. One in 5 participants experienced their first TBI injury before the age of 15 years. A regression model was able to correctly classify 66.9% of cases and revealed that belonging to Māori ethnicity or being imprisoned for violent, sexual or burglary offences were independently predictive of TBI (χ2 = 9.86, p = 0.28). Conclusions: The high prevalence of TBI within male prisoners and a high proportion of injuries sustained in childhood suggest the need for routine screening for TBI to identify prisoners at risk of persistent difficulties. Interventions to support those experiencing persistent difficulties post-TBI are needed to optimise functioning and prevent reoffending.