STEM education, which consists of the initials of the words Science, Technology, Engineering and Mathematics, is an educational approach that blends theoretical knowledge with engineering skills. The STEM education approach is implemented in the USA from preschool to senior high school through engineering design and interdisciplinary studies within the framework of the Next Generation Science Standards. The aim of this research is to determine the effect of STEM applications in preschool education on students' career goals and engineering perceptions. The case study, one of the qualitative research models, was used as the research model. The research was carried out for 12 h in 8 weeks with the participation of a total of 20 students, nine boys and 11 girls, in the preschool age group of five. Career Goal Setting Form was used as a data collection tool. As a result, it has been concluded that STEM applications in preschool education are effective on students' career planning. STEM applications have increased students' interest in STEM fields. STEM applications have given students new knowledge about the engineering profession and skills. STEM applications have been effective on students' product design/invention goal process.