This study aimed to examine the impact of transformational leadership practices of educational supervisors on the sustainable professional development of mathematics teachers in the Sultanate of Oman. To achieve the objectives of the study, the descriptive approach was adopted. The study's sample were 261 mathematics teachers. The researchers used the supervisors' practice of transformational leadership scale, and the researcher's sustainable professional development scale. The validity of the content of the two scales was measured through the validity of the terms and sampling validity. The reliability of internal consistency was also measured by the Alpha Cronbach. To ensure the factorial structure of the two scales, the researchers conducted a confirmatory factor analysis of the assumed model for each scale, and for the hypothetical model, and the results showed obtaining two models that match the current study data to large extent.The researchers used Structural Equation Modeling (SEM), where the results showed a positive and significant impact of transformational leadership practices for educational supervisors on the sustainable professional development of mathematics teachers in planning, curriculum, evaluation, professional development, and teaching methods.