The aim of this pilot study was to evaluate the acceptability and feasibility of delivering an online anxiety prevention program in schools, and to assess the effectiveness of the intervention in reducing symptoms of anxiety. Three schools located in South Australia and the Australian Capital Territory were recruited to participate in the trial, with classes randomly allocated to the intervention or wait-list control condition. All participants (N = 225) were invited to complete a pre-intervention, post-intervention and 3-month follow-up questionnaire. Participants in the intervention condition completed the online e-couch Anxiety and Worry program during one class period a week for six weeks. No significant differences were found between the intervention and control conditions at post-intervention or 3-month follow-up for generalised anxiety (Cohen's d = − 0.09–0.08), social anxiety (d = 0.09 & − 0.26), anxiety sensitivity (d = 0.19 & − 0.15), depressive symptoms (d = 0.01 & 0.08) or mental wellbeing (d = 0.17 & 0.30). Online anxiety prevention programs are acceptable and can be feasibly delivered in schools. Although not significant, the sizes of some of the effects obtained in this pilot trial are consistent with earlier studies, and warrant further investigation in a larger trial