Background: Addressing sexual trauma in the context of HIV care is essential to improve clinical outcomes and mental health among women in South Africa. Women living with HIV (WLH) report disproportionately high levels of sexual trauma and have higher rates of posttraumatic stress disorder. Adherence to antiretroviral therapy (ART) may be difficult for traumatized women, as sexual trauma compounds the stress associated with managing HIV and is often comorbid with other mental health disorders, further compromising care engagement and adherence. ART initiation represents a unique window of opportunity for intervention to enhance motivation, increase care engagement, and address the negative effects of trauma on avoidant coping behaviors. Mental health interventions delivered by non-specialists in low- and middle-income countries have potential to treat depression, trauma, and effects of intimate partner violence among WLH. This study will examine the effectiveness of Improving AIDS Care after Trauma (ImpACT +), a task-shared, trauma-focused coping intervention, to promote viral suppression among WLH initiating ART in a South African clinic setting. Methods: This study will be conducted in Khayelitsha, a peri-urban settlement situated near Cape Town, South Africa. Using a hybrid type 1 effectiveness-implementation design, we will randomize 350 WLH initiating ART to the ImpACT + experimental condition or the control condition (three weekly sessions of adapted problem-solving therapy) to examine the effectiveness of ImpACT + on viral suppression, ART adherence, and the degree to which mental health outcomes mediate intervention effects. ImpACT + participants will receive six once-a-week coping intervention sessions and six monthly maintenance sessions over the follow-up period. We will conduct mental health and bio-behavioral assessments at baseline, 4, 8, and 12 months, with care engagement data extracted from medical records. We will explore scalability using the Consolidated Framework for Implementation Research (CFIR). Discussion: This trial is expected to yield important new information on psychologically informed intervention models that benefit the mental health and clinical outcomes of WLH with histories of sexual trauma. The proposed ImpACT + intervention, with its focus on building coping skills to address traumatic stress and engagement in HIV care and treatment, could have widespread impact on the health and wellbeing of individuals and communities in sub-Saharan Africa. Trial registration: Clinicaltrials.gov NCT04793217. Retrospectively registered on 11 March 2021.