Administrative Assistant Teachers (AATs) in primary schools play an important role as middle leaders in managing and administrating the curriculum area, staff and are also responsible for leading teaching and learning activities in school. Their roles, functions and responsibilities must be clarified so that they can perform their duties efficiently. For that purpose, competency models are best used to guide the required knowledge, skills and values. However, research relating to the development of competency models for AATs especially in primary schools is considered new and has received less attention from scholars in Malaysia. Thus, this study aims to develop a competency model for AATs in primary school in Malaysia. The design of the study used a quantitative approach with the Fuzzy Delphi Method (FDM). FDM is more effective, systematic and best at gaining consensus on issues related to problem solving. A total of 26 experts were involved in this study. A questionnaire with a 7-point Likert scale is used as the research instrument. Data analysis showed that all FDM requirements were met with experts’ consensus exceeding 75%, threshold value, d < 0.2 and Fuzzy score value, α-cut exceeding 0.5. In conclusion, the final model consisted of four main constructs namely Self-Emotional, Governance, Leadership and Instructional. The findings also discovered that the resulting 57 competency elements fit the needs of AATs, which can also distinguish outstanding AATs in school. The implications of this study are significant for the Ministry of Education (MOE) Malaysia and can be utilized for the professional development of AATs through training modules or self-assessment of performance.