Objectives: The experience of psychosis and its sequelae (including treatment experiences) can be traumatic and affect feelings of safety and security. Until relatively recently, trauma therapy has been avoided with psychosis populations due to concerns about additional harm. Intervention-based research is growing, but focus on psychosis-related trauma is limited. Engendering psychological safety may support engagement with trauma-focused therapy, for which attachment theory provides a strong foundation. Imagery can enhance felt security and is an effective modality for working with trauma. Therefore, this study aimed to examine feasibility and preliminary outcomes of a novel attachment-focused imagery therapy (A-iMAPS) addressing psychosis-related trauma. Methods: A multiple baseline case series: Participants received between two and five baseline assessments then engaged in the six-session A-iMAPS intervention. Participants completed weekly measures of trauma symptoms and felt security. Further measures were completed pre- and post-intervention. Results: Twelve clinical participants were recruited from NHS services in Northwest England and eight retained through baseline and intervention to the end-of-therapy assessment (attending all sessions). A significant improvement was seen for felt security between baseline and intervention phases. Other measures of trauma symptoms, core schemas, paranoia and attachment varied in change from baseline to end of therapy, but some promising preliminary results were seen. Conclusions: This study shows that a brief attachment-focused imagery therapy is a promising intervention for targeting psychosis-related trauma, for which there are currently no other specific intervention studies. Utilizing an attachment-informed framework when working with trauma in psychosis should be considered in future intervention studies.