Exposure to prolonged and/or multiple types of psychological trauma and stressors has been shown to be more strongly associated with ICD-11 complex posttraumatic stress disorder (CPTSD) than posttraumatic stress disorder (PTSD). Lesbian, gay, bisexual, trans- and queer adults (LGBTQ+) are at a heightened risk of exposure to traumatic events, and minority stressors including harassment, discrimination, rejection by family, and isolation. Objective: To examine the factor structure of the international trauma questionnaire (ITQ), a self-report measure of PTSD and CPTSD, and the associations of cumulative lifetime trauma exposure assessed via the life events checklist and minority stress assessed via the daily heterosexist experiences scale, with CPTSD (three PTSD symptom clusters, three clusters reflecting disturbances in self-organization [DSO]) among LGBTQ+ adults. Method: Participants comprised 225 LGBTQ+ adults (including 74 transgender and gender diverse individuals; age range: 18–60 years; M/SD = 31.35/9.48) residing in Spain. Results: Confirmatory factor analyses indicated that both a first-order six-factor model and a hierarchical two-factor model, comprising PTSD and DSO as second-order factors, fit the data best. Cumulative traumatic events score was associated with PTSD, and cumulative minority stress was associated with PTSD and DSO. Among the minority stress subscales, harassment based on gender expression was positively associated with all symptom clusters of PTSD and DSO. Conclusion: This is the first study to examine the role of minority stressors alongside exposure to psychological traumas in ICD-11 PTSD and CPTSD and emphasizes the inclusion of minority stressors in trauma-related assessments.