The aim of this study was to examine the correlation between preservice teachers' cognitive flexibility levels and their teaching self-efficacy perceptions. Convenience sampling was used for the sample group of the study conducted according to the correlational survey model. The sample group consisted of 4th-year students who were studying in the departments of 'Computer and Instructional Technologies Education', 'Classroom Teaching', 'Art Teaching', 'Mathematics Teaching', 'Turkish Teaching', 'Social Studies Teaching', 'Preschool Teaching', and 'Science Education', under the body of Faculty of Education, Firat University during the 2019-2020 academic year. The "Cognitive Flexibility Scale", which was developed by Martin and Rubin (1995) and adapted into Turkish by Çelikkaleli (2014), and "Teachers' Sense of Efficacy Scale," which was developed by Tschannen-Moran and Woolfolk Hoy (2001) and adapted into Turkish by Çapa, Çakiroglu and Sarikaya (2005), were used as data collection tools in the study. The data were analysed using a computer-aided statistical program. Kolmogorov-Smirnov test was applied to meet the normality assumption of the data. Since the data met the assumption of normality, independent samples t-test was used to compare student views according to the variable of gender. Analysis of variance was used to make comparison based on the variables of department, grade point average and expectation to pass PPSE (Public Personnel Selection Examination). Pearson's correlation coefficients were used to determine the correlation between the scales. As a result of the study, both the cognitive flexibility levels and the levels of teaching self-efficacy perception were found to be high in preservice teachers. While the cognitive flexibility level of female preservice teachers was higher than male preservice teachers, the cognitive flexibility levels and teaching self-efficacy perceptions were higher than others in preservice teachers having a high grade point average and a high expectation to pass PPSE. Finally, it was determined that levels of cognitive flexibility and teaching self-efficacy perception affected one another positively and significantly.