People who hear voices (auditory verbal hallucinations) often have post-traumatic stress disorder (PTSD) symptoms. Cognitive behavioural therapies (CBT) have yielded inconsistent findings when treating voices and PTSD symptoms in voice hearers. Preliminary evidence suggests imagery rescripting (ImRs) is associated with large reductions in voice hearing and PTSD symptoms. This study replicated past studies using a larger sample to examine the effectiveness of ImRs in reducing such symptoms. Participants (N = 49; 65.3% female; Mage = 35.86) were clients at an Australian transdiagnostic clinic for voice hearers. A one-arm open trial design was used with three pre-treatment baselines and a mid-treatment, post-treatment and 3-month follow up assessments of PTSD symptoms (Posttraumatic Diagnostic Scale for DSM-5), voices (Hamilton Program for Schizophrenia Voices Questionnaire) and emotional symptoms (Depression Anxiety and Stress Scales-21). Five single-item measures were administered weekly to explore the trajectories of change in trauma intrusions, voice-related distress, voice frequency and positive and negative voice valance. ImRs was associated with very large reductions in PTSD symptoms and voices (both emotional and physical characteristics of voices) and emotional symptoms at post-treatment and follow-up (η2 p = 0.24-0.44). There were medium-large to large reductions in weekly symptoms of intrusions, voice-related distress, voice frequency and negative voices (η2 p = 0.12-0.16) and a non-significant increase in positive voices (η2 p = 0.05). This study provides further evidence that ImRs is an effective treatment for voices and PTSD symptoms in voice hearers with a range of diagnoses. Randomised controlled trials are needed to compare the efficacy of ImRs to CBT protocols.