The general education curriculum issued in 2018 is being implemented, with many advantages in integrating STEM education into learning subjects and topics, contributing to the development of students’ qualities and capacities. STEM Day is a celebration of Science, Technology, Engineering, and Mathematics. Its primary goal is to inspire and engage students in these fields, sparking an interest in future STEM careers and innovations. This article presents the process of organizing a STEM Day for students, including three stages: the stage before, the stage during, and the stage after STEM Day. By embracing the three organizing stages mentioned, we can engage students, parents, and the community with STEM education in a meaningful way, discover students’ passions, and potentially lay the foundation for future careers in these essential fields.