The aim of this study is to determine the self-efficacy perceptions of primary school teachers towards teaching thinking skills and whether these perceptions differ significantly in terms of various variables and to determine the views of primary school teachers about their self-efficacy perceptions towards teaching thinking skills. In the research using mixed research method, explanatory sequential design was preferred. The sample regarding the quantitative dimension of the research consists of 371 primary school teachers, who were determined by cluster sampling method from the teachers working in primary schools in the center of Sivas in the spring term of the 2021-2022 academic year. The study group reached for the qualitative dimension of the research consists of 41 primary school teachers, who were determined by the maximum diversity sampling method from the teachers working in primary schools in the centre of Sivas during the same academic period. “Teachers’ Self-efficacy towards Teaching Thinking Skills Scale (TSTTS)” developed by Dilekli and Tezci (2015) and a semi-structured interview form consisting of three questions developed by the researchers were used as data collection tools. In the research, descriptive statistics, independent samples t-test and one-way ANOVA test were used in the analysis of quantitative data, and content analysis method was used in the analysis of qualitative data. When the data obtained from the scale are evaluated; teachers’ self-efficacy perceptions regarding teaching thinking skills were at the level of “totally agree”; that these self-efficacy perceptions of teachers did not differ according to gender, faculty, and department from which they graduated, and the class taught. It was found that the teachers’ self-efficacy perceptions differed according to the variable of professional seniority in the whole scale with the factors of “Practice”, “Academic competence”, and this difference was in favor of teachers with a professional seniority of 1-10 years and teachers with a professional seniority of 21 years and above, in favor of teachers with a seniority of 21 years and above. When qualitative data are evaluated, it was understood that teachers take into account individual differences, design real- life examples, make plans, and design different thinking activities related to the design factor when teaching thinking skills. In the practice factor, it was determined that they perform different thinking activities and use different teaching methods and techniques. In addition, it was concluded that most of the teachers perceive themselves as competent in teaching thinking skills, while some teachers do not see themselves as competent.