This study aims to examine the satisfaction of Vietnamese K-12 teachers with the impact of Teacher Activity Groups (TAGs) on their professional development (PD). In the context of a rapidly evolving education system, PD plays a crucial role in enhancing teachers’ knowledge, skills, and effectiveness in the classroom. Collaborative approaches, such as TAGs, have gained attention as promising strategies for fostering teacher growth and satisfaction. However, limited research has explored the specific impact of TAGs in the Vietnamese context. To address this gap, a quantitative approach was employed, and data were collected using a questionnaire from 147 K-12 teachers. The questionnaire consisted of 21 items measured on a 5-point scale, assessing various aspects of participants’ satisfaction with the TAGs program. The results reveal high levels of overall satisfaction with the TAGs program, indicating positive perceptions of its interest, value, usefulness, and impact on professional development. Notably, variations in satisfaction levels were observed in relation to learner attendance and dropout rates. These findings provide valuable insights for educational policymakers and school administrators in designing and implementing effective PD initiatives tailored to the specific needs of teachers and students. By promoting teacher satisfaction and growth, TAGs have the potential to contribute to the continuous improvement of the Vietnamese education system.