<p>Teachers’ mathematics-related beliefs have a substantial influence on their teaching. Given the variety of opportunities for teaching mathematical modeling supported by digital tools, related beliefs are crucial for classroom implementation. In this paper, we introduce a course that aims to prepare future mathematics teachers for teaching mathematical modeling in school using digital tools (focusing here on MathCityMap as an example). We used linear mixed models to analyze the development of 54 preservice teachers’ beliefs over the course, comparing them with 58 mathematics preservice teachers who did not attend the course. Results show an increase in course participants’ self-concepts about digital tools and mathematical modeling, as well as a tendency toward a more dynamic and less static mathematical worldview. There are hints that different course units contribute differently to the development of beliefs. These results suggest that such a course can provide a foundation for teachers to integrate digitally supported mathematical modeling into the classroom.</p>