This mixed-methods study employed an explanatory sequential design to examine the impact of play-based STEM activities on preschool children’s problem-solving skills and to explore parents’ and teacher’s views on the developmental benefits of these activities. The quantitative component aimed to measure changes in children’s problem-solving skills using a validated scale. Meanwhile, the qualitative component provided in-depth insights into the experiences of the children, parents, and teachers through semi-structured interviews. The intervention was implemented in a public preschool with 19 children in the experimental group and 16 in the control group over eight weeks. Quantitative data were collected using the Problem-Solving in Science Education Scale, and qualitative data were collected through semistructured interviews with children, parents, and a teacher. The results indicated significant improvements in the experimental group’s problem-solving abilities, with large effect sizes for material usage problems and total scores, and a medium-to-large effect size for science and nature problems. The qualitative findings revealed that children enjoy design-based activities, demonstrate persistence when facing challenges, and transfer learning to home contexts. The parents reported enhanced cognitive, social-emotional, and motor skills, while the teacher highlighted increased curiosity, creativity, and teamwork. The implementation challenges included time constraints, initial teamwork difficulties, and sustained attention. The study underscores the potential of play-based STEM education to promote holistic development in early childhood and provides implications for teachers, parents, and curriculum designers.