Intimate partner violence (IPV) is a serious mental and physical health concern worldwide. Although previous research suggests that childhood maltreatment increases the risk for IPV, the underlying psychological mechanisms of this relationship are not yet entirely understood. Borderline personality (BP) features may play an important role in the cycle of violence, being associated with interpersonal violence in both childhood and adult relationships. The present study investigated whether BP features mediate the relationship between childhood maltreatment and IPV, differentiating between perpetration and victimization, and taking maladaptive stress coping and gender into account. Self-reports on IPV, childhood trauma, BP features, and maladaptive stress coping were collected in a mixed (nonclinical and clinical) sample of 703 adults (n = 537 female, n = 166 male), using an online survey. A serial mediation analysis (PROCESS) was performed to quantify the direct effect of childhood maltreatment on IPV and its indirect effects through BP features and maladaptive coping. Childhood maltreatment severity significantly positively predicted IPV perpetration as well as victimization. BP features, but not coping, partially mediated this relationship. Follow-up analyses suggest that affective instability and interpersonal disturbances (e.g., separation concerns) play an important role in IPV perpetration, while interpersonal and identity disturbances may mediate the effect of childhood maltreatment on IPV victimization. In clinical practice, attention should be paid not only to histories of childhood abuse and neglect but also to BP features, which may be possible risk factors for IPV.