Reoffending rates after release from prison are high in most Western countries. Knowledge on how certain aspects of prison life affect postrelease recidivism could be useful to effective crime-control. One aspect of prison life that may potentially affect prisoners’ reoffending behavior refers to the extent to which prisoners feel treated fairly and respectfully. This notion is central to procedural justice theories, which argue that people will be more likely to comply with the law when they feel treated in a just and decent way by actors who enforce the law. At present, it is unknown whether or not a procedurally just treatment during imprisonment can reduce postprison reoffending rates. This study examined (a) whether prisoners’ procedural justice perceptions influence their postrelease offending behavior, and (b) whether the relationship between procedural justice and reoffending was mediated by prisoners’ perceived legitimacy of the criminal justice system. Associations were explored with survey and registered conviction data of 1,241 Dutch prisoners from the Prison Project. Although the effect was small, prisoners who felt treated in a procedurally just manner during imprisonment were less likely to be reconvicted in the 18 months after release. No evidence was found for a mediating role of legitimacy.