Objective: Ten-session cognitive behavioural therapy (CBT-T) for transdiagnostic eating disorders targets several barriers to treatment, including cost, therapist expertise, and lengthy wait lists.Method: We used a case series design to investigate the effectiveness of CBT-T delivered by trainee psychologists in a postgraduate training clinic.Participants were randomly allocated to commence treatment either immediately or after a 4-week waitlist period. CBT-T was delivered to 52 patients, by six different trainees under supervision. Measures of eating disorder cognitions and behaviours, quality of life, and general psychopathology were examined in completer and intention-to-treat analyses using multilevel modelling. Last observation carried forward was applied for abstinence, remission, and good outcome analyses to aid comparison with prior studies.Results: Significant improvements, associated with medium to large effect sizes, were found for eating disorder cognitions, behaviours quality of life, and negative affect from baseline to posttreatment, and at 1-and 3-month followup. Attrition (38.5%) was comparable with other treatment studies.Conclusion: Results provide evidence for the effectiveness of CBT-T delivered by trainee psychologists for transdiagnostic eating disorder patients, thus tackling some important barriers for treatment. Longer follow-up, randomised controlled trial designs, and moderator analyses will provide more robust evidence about which patients do best with a shorter therapy.