Trauma informed care (TIC) is a whole system organisational change process which emerged from the seminal Adverse Childhood Experiences (ACE) study, establishing a strong graded relationship between the number of childhood adversities experienced and a range of negative outcomes across multiple domains over the life course. To date, there has been no systematic review of organisation-wide implementation initiatives in the child welfare system. As part of a wider cross-system rapid evidence review of the trauma-informed implementation literature using systematic search, screening and review procedures, twenty-one papers reporting on trauma-informed implementation in the child welfare system at state/regional and organisational/agency levels were identified. This paper presents a narrative synthesis of the various implementation strategies and components used across child welfare initiatives, with associated evidence of effectiveness. Training was the TIC implementation component most frequently evaluated with all studies reporting positive impact on staff knowledge, skills and/or confidence. The development of trauma-informed screening processes, and evidence-based treatments/trauma focused services, where evaluated, all produced positive results. Whilst weaknesses in study design often limited generalisability, there was preliminary evidence for the efficacy of trauma-informed approaches in improving the mental and emotional well-being of children served by community-based child welfare services, as well as their potential for reducing caregiver stress and improving placement stability.