The present study aimed to determine the effectiveness of integrative transdiagnostic therapy on anger, rumination, and perceived stress in middle-aged teachers. The research method was a quasi-experimental design with a pretest-posttest design with a control group. The statistical population included all middle-aged teachers (40 to 60 years old) working in schools in Semnan in the academic year 1404-1405. Thirty people were selected by convenience sampling and randomly assigned to two experimental groups (15 people) and control groups (15 people). The experimental group underwent integrative transdiagnostic therapy for 12 90-minute sessions, while the control group did not receive any psychological intervention. Data collection tools included the Spielberger State-Trait Anger Expression Inventory (STAXI-2), the Nalen-Hoeksma and Maro Rumination Questionnaire (RRS), and the Cohen Perceived Stress Scale (PSS).The data were analyzed using multivariate and univariate analysis of covariance at a significance level of 0.05. The findings showed that after controlling for the effect of pre-test scores, there was a significant difference between the experimental and control groups in all research variables (P<0.01). Integrative transdiagnostic therapy significantly reduced anger, rumination, and perceived stress in the experimental group compared to the control group. Based on the research findings, it can be concluded that integrative transdiagnostic therapy can be used as an effective psychological intervention in reducing emotional problems in middle-aged teachers by improving emotion regulation skills, reducing rumination and stress, and improving anger management. Therefore, the use of this approach in teacher empowerment programs and education counseling centers is recommended.