<p>Plurisexual women (i.e., women who are attracted to multiple genders) are at significantly higher risk for sexual victimization than monosexual women across the lifespan. Our study extends ecological models of sexual violence, minority stress theory, and traumagenic theory to this crucial high-risk population. Specifically, we test the hypothesis that a history of sexual abuse in childhood shapes women’s schemas of their sexual selves as “immoral” and “irresponsible,” which then increases vulnerability to sexual victimization in adulthood, particularly among individuals who experienced higher levels of sexual identity stigma. Participants included 229 plurisexual-identifying women (M_age = 28.42) from North America and the United Kingdom, recruited through the online platform Prolific Academic. All constructs were assessed via self-report questionnaires. Results supported the hypothesized moderated mediation model: the significant, positive indirect association between childhood sexual abuse and adult sexual victimization severity, through scores on the “immoral-irresponsible” self-schema, was significantly stronger among those reporting higher antibisexual stigma (Index = 0.02, 95% CI [.0004, .05]). Further, a lower schema of the sexual self as “open-direct” was also associated with higher severity of adult sexual victimization, again among those reporting higher antibisexual stigma (<i>b</i> = − 0.12, <i>p</i> = .01). These findings suggest that external stigmatization amplifies the impact of negative internalized self-beliefs on vulnerability to adult sexual victimization. Thus, these novel findings underscore the importance of considering both individual difference factors and broader systemic and societal influences when exploring the complex dynamics of sexual victimization in sexual minority women.</p>