Background: Betrayal trauma, as defined by (Freyd, 1996), refers to a subcategory of trauma characterized by a significant violation of trust surrounding interpersonal maltreatment (physical, sexual, or emotional). Previous research has shown that people with betrayal trauma histories experience greater dissociative symptoms of posttraumatic stress disorder and co-morbid substance use disorder symptoms. Women in the criminal legal system commonly have significant histories of betrayal trauma and related posttraumatic stress symptoms and substance use. However, no studies have specifically explored the impact of dissociative posttraumatic stress symptoms on substance use outcomes in this population. Additionally, no studies have explored whether betrayal trauma relates to nonfatal overdoses. Methods: This cross-sectional survey study of N = 508 women with criminal legal system involvement examined the indirect effects of betrayal trauma history on substance use outcomes through dissociative posttraumatic stress symptoms. Results: Multivariate analyses supported an indirect effect of betrayal trauma on substance use severity, daily substance use, and history of overdose, but not alcohol use severity, through dissociative symptoms. Conclusions: Women in the criminal legal system with betrayal trauma and dissociative symptoms may be at risk for substance use and related outcomes (i.e., overdose). Future work is needed to examine whether targeting such symptoms may improve substance use treatment and prevention of serious outcomes in this population.