This study investigates the effectiveness of project-based STEAM activities on preschool children's product creation, teamwork, presentation, and engineering skills. The research is based on the technical/scientific/collaborative action research model. In determining the participants of this study, the criterion sampling method was used, one of the purposeful sampling methods. Three preschool teachers first received hands-on STEAM trainer training for two and a half months and then carried out activities following the six-week STEAM education model with 57 children in the preschool period according to their education. It was concluded that in-class STEAM activity practices had a lasting positive effect on preschool children's social product, teamwork, presentation, and engineering skills. In conclusion, it can be said that the STEAM approach can be effective in preschool.