This study aims to explore and analyze the experiences of teachers who participated in the Elementary School Level 1 Teacher Certification Training Program. This program was commissioned by the Gyeonggido Office of Education in 2024 to A Education University, a teacher training institution. Semi-structured in-depth interviews were conducted on six elementary school teachers, and the data were analyzed using phenomenological research methods. The findings revealed four key meanings derived from the teachers’ experiences: (1) enhancement of teacher professionalism, (2) formation of collaboration and bonds, (3) gap between theory and practice, and (4) discomfort and challenges faced during the program. To further foster teacher’s professionalism, this study also discussed the potential areas for improvement in future training programs. Moreover, this study highlighted the importance of the Elementary School Level 1 Teacher Certification Training Program in enhancing teacher’s professionalism. The significance of this study lies in its in-depth analysis of the experiences of teachers who participated in the 2024 Gyeonggi Elementary School Level 1 Teacher Certification Training Program, which was distinct from previous programs as it was commissioned by a teacher training university.