Toys used as a play tool have an important role in the development of children. For this reason, it is necessary to offer children the opportunity to design their own toys. Scientific toys can be used in science lessons to encourage creativity and to teach science concepts and scientific inquiry. With the integrated STEM Education and specifically Engineering Design Process, children can have the ability to design their toys according to their own creativity, while at the same time they can gain many skills through scientific studies. The integration of these designs into education will contribute to the development of engineering skills perceptions and scientific creativity. This study aims to examine the effect of scientific toy design activities based on engineering design process on the scientific creativity of middle school students' and their views on scientific toy design activities. The research conducted for this purpose was carried out over a 9-week period. The study group consists of 40 middle school 7th grade students. The research was carried out with a single group pre-test post-test experimental design method. "Scientific Creativity Test" was used to collect the data. Data were analysed using quantitative and qualitative analysis techniques. As a result of the research, it was determined that the scientific creativity of middle school students improved positively with scientific toy design activities based on the engineering design process.