Research supports a strong relationship between childhood maltreatment and internalizing psychopathology (e.g., anxiety and depression), and features of personality are assumed to explain some of this relationship. In this study, we proposed a model in which maladaptive traits mediate the effect of childhood trauma history on internalizing symptoms in adult individuals. A mixed sample (N = 462) composed of 142 psychiatric patients and 320 community-dwelling individuals completed the Childhood Trauma Questionnaire (CTQ), the Personality Inventory for DSM-5 (PID-5), and the Symptom Checklist (SCL-27) for internalizing psychopathology. The effect of childhood traumas explained 34% of the variance in internalizing symptoms while controlling for the influence of age and gender. The traits accounted for 78% of this effect, which was predominantly exerted through the domains of Negative Affectivity, Detachment, and Psychoticism, and specifically through the facets of Depressivity, Suspiciousness, Anxiousness, Perceptual Dysregulation, and Distractibility. This finding provides preliminary support for the proposed model indicating that the aforementioned maladaptive trait domains potentially function as mediating links by which childhood traumas are translated into internalizing symptoms in adulthood. However, these findings must be interpreted with caution due to the cross-sectional and retrospective mono-method design of this study. Clinical implications are discussed in relation to transdiagnostic treatment and the potential value of specifying trait domain specifiers in ICD-11 and DSM-5 models of personality disorders.