Background Recently released prisoners are at markedly increased risk of death and drug-related causes predominate. Non-fatal overdose (NFOD) is considerably more common than fatal overdose, but has received relatively little research attention and most studies of NFOD in this population have suffered from small samples of unknown representativeness. This study aimed to estimate the prevalence and correlates of lifetime NFOD among prisoners in NSW and Queensland. Methods Cross-sectional surveys of adult prisoners in two Australian states: New South Wales (n = 972) and Queensland (n = 1316). Use of similar measures and methods in the two states made direct comparison of findings possible. Results In both NSW and Queensland, 23% of participants reported a lifetime history of NFOD and prisoners with a history of injecting drug use were significantly more likely to report lifetime NFOD. The lifetime prevalence of NFOD among prisoners with a history of injecting drug use was significantly higher in NSW than in Queensland (44% vs. 35%; p < 0.01). Independent correlates of lifetime NFOD were similar across the two states and included ever attempting suicide, ever injecting heroin, and ever injecting opioids. Conclusions The risk of NFOD among prisoners with a history of injecting drug use is high. An understanding of the risk factors for NFOD in this population can inform targeted, evidence-based interventions to reduce this risk.