Over the last two decades, computational thinking (CT) has gained importance in discussions about competencies that students require to deal with complex problems in a world shaped by digitalization. Therefore, schools and teachers should integrate CT into their instructional practices. Particularly, the STEM (Science, Technology, Engineering, and Mathematics) subjects are seen as a meaningful context for embedding CT. Yet, there are only a few professional development programs that address STEM teachers and how to integrate CT. Thus, in our study, we redesigned an in‐service teacher training program. The redesigned program was offered in a blended‐learning format, consisting of alternating digital and face‐to‐face phases. As part of the digital phases, an interactive online self‐learning module on CT was introduced to foster transdisciplinary competencies in the field of STEM to solve complex problems. To identify the perceptions and development of the participants of the training program and the online module on CT a within‐subject design was used with a questionnaire survey, conducted with a pre‐post‐follow‐up design. The first results of the ongoing survey indicate high satisfaction with both the program itself and the online CT module. At the beginning of the program, about two‐thirds of the participating teachers were completely unfamiliar with the term CT, nevertheless, interest in the new topic was high. It was shown the program was able to create initial awareness of the meaning and importance of CT. In addition, teachers who have engaged with CT during the intervention seem to use CT‐related practices more often in the classroom afterward.