Enhancing science, technology, engineering, and mathematics (STEM) education requires a comprehensive understanding of the practical challenges encountered by teachers during implementation. This research study aimed to uncover valuable insights into the integration of STEM education in Vietnam as perceived by primary school teachers. Employing a mixed method approach, the study engaged 454 teachers and administrators from primary schools across the northern, central, and southern regions of Vietnam. Data were collected through interviews and an online survey, focusing on the challenges and needs of teachers in organizing STEM educational activities. Findings reveal that elementary school teachers in STEM education face challenges such as professional competency, program methodologies, resource availability, time and space constraints, and the need for a comprehensive STEM ecosystem. The primary school teachers expressed a strong desire for professional development support, encompassing: (a) increased opportunities for experiential learning, collaboration, and knowledge-sharing among colleagues, supplemented by expert-led training sessions on STEM skills implementation; (b) a preference for practical training courses, sharing of real-world experiences, and a need for continuous and regular professional development activities, as opposed to sporadic training sessions; (c) provision of financial support and conducive conditions to facilitate ongoing professional growth; and (d) assistance in leveraging technology for effective STEM education. These research findings serve as a vital foundation for educational managers and teacher training institutions to formulate policies and implement support mechanisms that are essential for the success of STEM education.