Previous research has established that people with severe mental illness and co-occurring substance use disorder leaving prison have multiple and complex health, social and economic challenges. How the criminal justice and mental health systems influence the individual prison-to-community transition experience of this population is less well understood. This paper draws on unique qualitative data from a study of 18 men with co-occurring severe mental illness and substance use disorder leaving prison in Queensland, Australia. A repeat in-depth interview method was used to explore the experiences of the men in prison just prior to release and at two points post-release. Two themes are discussed from analysis of interviews: “risk behaviour and relapse” and “once a criminal always a risk”. The findings suggest that individual risk behaviour is structured within a transition risk environment that reduces individual agency, thus facilitating a vicious cycle of release, relapse and reincarceration.