Background: Psychological distress is an unpleasant mental state characterized by stress, low mood, anxiety, and depression that impairs people’s mental health and their functioning. Objectives: This study aimed to evaluate the effects of stress management training on the psychological distress and academic achievement of university entrance exam applicants. Methods: This quasi-experimental pretest-posttest study with follow-up was conducted on all the students preparing for the Iranian University Entrance Exam in Ahvaz, Iran, in 2022. A total of 30 eligible participants were selected using convenience sampling and randomly assigned to the intervention and control groups (15 per group). The intervention group received eleven 120-minute sessions of cognitive-behavioral therapy (CBT)-based stress management training, whereas the control group received no training. The Educational Performance Test and Psychological Distress Questionnaire were used to collect data. Data were analyzed using SPSS 25 software and descriptive and inferential statistics. Results: Stress management training improved the treatment group’s psychological distress and academic achievement at the post-test and follow-up stages (P < 0.001). The results showed significant differences between the intervention and control groups following stress management training (P < 0.001). Conclusions: Based on the results, stress management training could improve the psychological distress and academic achievement of people facing stressful events such as university entrance exams.