Background Child sexual abuse (CSA) has been linked to a higher risk of sexual re-victimization, including sexual intimate partner violence (IPV). The aim of this study was to investigate whether borderline personality disorder (BPD) features, dissociation, and maladaptive cognitive emotion regulation mediate the link between self-reported CSA severity and sexual IPV. Specifically, we were interested in the unique effect of each mediator variable, when accounting for the effect of the other variables. Methods Data was assessed in a cross-sectional anonymous online survey, posted on platforms for people affected by domestic violence, and research platforms of Leiden University. Overall, n = 633 participants completed the survey (including n = 100 participants with CSA and n = 345 reporting at least one incidence of sexual IPV). Multivariate regression analyses and path-analytical modelling were performed for hypothesis testing. Results Adult sexual IPV was predicted by more severe CSA, more severe BPD features, higher dissociation, and more maladaptive emotion regulation. Each mediator variable showed a significant effect in the separate mediation models. In the overall model, only dissociation and maladaptive emotion regulation, but not BPD features, mediated the association between CSA and sexual IPV. Conclusions Findings add to the existing literature, suggesting that CSA severity, BPD features, dissociation, and maladaptive emotion regulation are important risk factors for sexual IPV. Given the cross-sectional correlational design of our study, prospective studies are needed to corroborate our findings regarding potential psychological mechanisms underlying sexual re-victimization. Ultimately, this can help developing interventions aimed at breaking the cycle of abuse.