This study examined the relationship between adolescents’ cognitive flexibility and educational stress and the mediating role of perception of teacher acceptance on this relation. The study was based on a sample of 331 high school students in Turkey (145 male and 186 female). The age of students ranged from 14 to 18 years (Mage =16.12, SD=1.26). The child version of the Teacher Acceptance-Rejection/Control Questionnaire, Cognitive Flexibility Scale, Educational Stress Scale, and the Personal Information Form were used as measures. The results show that female students’ perception of teacher acceptance, and educational stress level were significantly higher than male students. Resuts also show that educational stress was significantly correlated with perception of teacher acceptance, cognitive flexibility, and age negatively. Finally, the result of the mediation analysis revealed that perception of teacher acceptance mediated the relationship between cognitive flexibility and educational stress. The results are discussed based on literature, and suggestions for researchers and practitioners were proposed.