This research aims to analyze the relationship between pedagogical formation training certificate program prospective teachers’ critical thinking attitudes and their perceptions on professional ethical principles. The study used relational screening model and convenience sampling method which is one of the purposeful sampling methods. The participants consisted of 393 prospective teachers from different majors such as mathematics, physics, chemistry, health, biology, philosophy, religious culture, Turkish language and literature, music, painting and ceramics. The study deployed two data collection tools and personal information form. Thinking Attitude Scale and Code of Professional Ethics Scale. Descriptive statistics, Pearson product-moment correlation, multivariate variance analysis were used during the data analysis. Research results have indicated a medium level of relationship between the critical thinking attitude of prospective teachers and their professional ethical principles. Also, the dimensions of critical thinking attitudes such as willingness to collect information, self-regulation, inference, evidence-based decision making and openness to seek reasons dimensions were found to have a significant relationship with the professional ethical principles, and the five variables account for about 13% of the professional ethical principles. Taking the significance tests of the regression coefficients into consideration, the dimensions of willingness to collect information, self-regulation and openness to seek reasons are regarded as the significant predictors of the professional ethical principles. Based upon the research findings, the following recommendations are provided: The availability of critical thinking and democratic education courses within the teaching certificate program or the inclusion of critical thinking and professional ethical principles in the pedagogical formation courses based on the subject will provide prospective teachers to have positive critical thinking attitudes and professional ethical principles. As a result, they will ensure students to gain critical thinking skills during the teaching process, and they are to show ethical behaviors towards their profession. Critical thinking and professional ethical principles can be examined via experimental and qualitative researches and different measurement tools. Article visualizations: