Early estimates point to higher rates of cognitive impairment among Indigenous Australians in custody compared to non-Indigenous Australians. This study sought to examine the prevalence of cognitive impairment in a representative sample of Indigenous offenders from Victorian prisons. Differences in mental illness prevalence, offending history and post-release recidivism were explored by presence of cognitive impairment. Results revealed an over-representation of cognitively impaired prisoners in the sample and a large minority with concomitant mental illness or disability. Cognitively impaired prisoners were more likely to re-offend, were younger at first offence, and had greater numbers of prior offences. Findings signal the need for culturally themed disability assistance and diversionary options at all levels of the criminal justice system.