The aim of this study is to examine the effect of the STEM approach on the scientific creativity, scientific process skills and 21st century skills of pre-service teachers who perform STEM applications within the scope of the "Science Teaching Laboratory Applications I" course. In the study, a single group pre-test-post-test weak experimental design was used. The study was carried out with 29 science teacher candidates studying in the 3rd grade of a state university in Balıkesir province in the 2024-2025 academic year. In the study, "Scientific Creativity Test", "Scientific Process Skills Test" and "Multidimensional 21. Century Scale'' was used; These scales were applied to pre-service teachers before and after the application. SPSS 20.0 statistical program was used to analyze the obtained data. Since the data did not adapt to the normal distribution, they were analyzed by Wilcoxon signed ranks test. In line with the findings obtained, although it was seen that the STEM approach did not make a significant difference in all three skill areas, it was also observed that the total scores of the pre-service teachers had a positive increase in these skill areas. As a result of the study, suggestions were made on how pre-service teachers can benefit more from such practices.