The present study was conducted with the aim of investigating the effectiveness of unified transdiagnostic group therapy on cognitive emotional regulation in patients with anxiety disorders. The current research was semi-experimental with a pretest-posttest design and a control group. The statistical population of the research included all individuals with anxiety disorders referred to one of the clinics in Mashhad, who had been referred to this clinic for treatment from October to December 2022. 30 participants in this research were selected from about 100 patients by voluntary sampling method and were replaced in two experimental and control groups. Subjects in two stages of pre-test and post-test with Anxiety Inventory (BAI) Beck et al. (1988) and DSM-5-TR diagnostic criteria, Persian version of the Cognitive Emotion Regulation Questionnaire (CERQ-P) Garnefski & Kraaij (2006) were measured. The intervention group received 8 sessions of 90 minutes as one session per week of unified transdiagnostic treatment. Data analysis was done using multivariate covariance analysis. Data analysis showed that by controlling the effect of the pre-test, there was a significant difference at the level of 0/05 between the post-test mean of cognitive emotional regulation including self-blame, rumination, catastrophizing, other-blame, acceptance, positive refocusing, refocus on planning, positive reappraisal and putting in the two experimental and control groups. Therefore, it can be concluded that group-based Unified transdiagnostic therapy can be effective in cognitive-emotional regulation.