Background/purpose: The Computational Thinking ability has become a fundamental skill in the 21st century and has been integrated into educational curricula in various countries. For this curricular integration to be effective, it is essential that teachers are prepared to incorporate the development of this competency into their practices. In this context, this study aims to analyze whether a training program implemented over an extended period, encompassing theoretical, practical, and reflective components, has influenced preservice teachers' perceptions of the competencies of Creativity, Algorithmic Thinking, Cooperativity, Critical Thinking, and Problem-Solving within Computational Thinking. Materials/methods: This is a mixed-methods study, using both quantitative and qualitative methods to analyze the perception of the Computational Thinking competence levels of 38 pre-service primary school teachers, who constitute the sample of this study, before and after the implementation of a 9-month training program. Results: The study results revealed statistically significant differences in all the competencies analyzed from the Pre-Intervention to the Post-Intervention phases. The data collected during the intervention highlight the specific moments within the training program that contributed to the development of each competency. Conclusion: It is concluded that the training program significantly contributed to changing the pre-service teachers' perceptions of the five Computational Thinking competencies analyzed. This highlights the importance of incorporating training programs into Initial Teacher Training, especially those that integrate theory and practice, fostering the development of essential competencies for the teaching practices of pre-service teachers.