• Design thinking STEM education increased children's creative thinking and problem-solving skills. • Children with adaptation problems can now establish better relationships with their friends. • Small groups increased communication and interaction. • Children were able to transfer what they learned at school to their lives. • Teachers' workload decreased, the transition from a teacher-centered process to a child-centered approach. The teacher is in the position of a guide. In this study, the effect of preschool STEM education prepared according to the design thinking model on children's creativity and problem-solving skills was examined. An experimental design in which pre-test-post-test and permanence test were applied was used in the research. The research was conducted with 20 children in the experimental group and 19 children in the control group. Design Thinking STEM Activities were completed 3 days a week with 8 weeks and 24 activities. As a result of the analysis, it was concluded that there was a significant increase in the experimental group's creativity and problem solving scores and this increase was permanent. On the other hand, creativity and problem solving pre, post and permanence test results of the control group were compared and it was seen that there was no significant difference between these tests. Also, STEM education, which is applied as a result of the data obtained from research diaries, increases communication and interaction skills in children, contributes to peer learning, supports cooperation, increases children's self-confidence, gains a sense of responsibility, encourages problem-solving and idea generation, and improves empathy skills. Suggestions were made in line with the results obtained in the study and the aims of the research.