Objectives Exposure to repeated traumatic events during childhood and adolescence is associated with high prevalences of mental illness, addictions, physical health conditions, and psychosocial difficulties (Felitti et al., 2019). The most common consequence of exposure to trauma is violence towards self and others (Hughes et al., 2017). The very high prevalence of complex trauma among forensic mental health service users challenges these settings to modify their practices, training approaches, policies, and service delivery approaches. The objective of this article is to contribute to such a transformation of forensic mental health services by clarifying the impacts of complex trauma on the trajectories and experiences of forensic mental health services users, as well as practices responding to complex trauma. Methods We reviewed the published and grey literature on complex trauma among forensic mental health service users. After synthesizing the findings, they were contrasted with our experiences as clinicians and researchers in the field of forensic mental health care through the development of a case vignette. Results We first identify the role of complex trauma and victimization in the development and maintenance of violent behaviours. We describe the negative experiences of services and care settings reported by individuals with complex trauma in the absence of recognition and understanding of traumatic experiences and their impacts. We highlight the fundamental principles of trauma-informed care (trust and transparency; safety; peer support; collaboration and reciprocity; empowerment and choice; sensitivity to gender, cultural and historical differences), as well as the clinical and organizational approaches emerging from those principles. Next, we describe the approaches developed internationally to apply and implement trauma-informed care in forensic mental health setting, and the opportunities and challenges associated with their implementation in the Québec context. Conclusion To date, few studies have documented and evaluated the implementation of trauma-informed care in forensic mental health settings. The literature reviewed in this paper indicates that an in-depth understanding of complex trauma among forensic mental health service users should be at the core of contemporary forensic research, policies and practices.