This study examined whether interdisciplinary hands-on experiences could influence preservice secondary mathematics teachers’ intentions to implement iSTEM teaching. Using the theory of planned behaviour, it explored how workshop evaluations and related psychological factors contributed to intention changes. A four-session interdisciplinary workshop was provided, leading to significant increases in participants’ perceived behavioural control and intentions to teach iSTEM. Evaluations of the workshop notably impacted attitudes, subjective norms, and control, which in turn influenced intention changes. The findings highlight the potential of short-term workshops to shape preservice teachers’ planned STEM teaching behaviours. Further research is recommended to optimize such workshops for diverse teacher backgrounds.