UNLABELLED: Healthcare workers are at increased risk of posttraumatic stress disorder (PTSD), depression and generalised anxiety disorder. Evidence-based interventions tailored to this workforce are limited. We developed and evaluated a telephone-based cognitive therapy coaching intervention targeting PTSD and depression. One hundred three healthcare workers seeking support during the COVID-19 pandemic completed measures at baseline, after three-week symptom monitoring, following six-week coaching, and at three-month follow-up. Sixty-five participants met criteria for probable PTSD (PCL-5 ≥ 32) or probable depression (PHQ-9 ≥ 10), and 38 experienced subthreshold symptoms. For PTSD (PCL-5) and depression (PHQ-9), reliable recovery rates increased substantially from symptom monitoring (PTSD: 14.6%; depression: 15.8%) to intervention (PTSD: 77.1%; depression: 64.3%), with sustained recovery at three months (68.8% and 52.6%, respectively). Overall, rates of reliable improvement increased from 41.1% to 65.8% for PTSD and from 20.0% to 63.1% for depression during intervention, with gains maintained at follow-up (72.2% and 56.0%, respectively). Mean PTSD, depression and anxiety (GAD-7) scores fell below clinical thresholds post-intervention and remained below at follow-up. Intervention-specific effects were observed for sleep, resilience, and wellbeing, with sustained improvements at follow-up. Cognitive therapy coaching is a promising intervention for healthcare workers with PTSD and depression symptoms. A randomised controlled trial is warranted. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-36057-5.