The quality of performance evaluation of school principals plays an unprecedented role in enhancing or ruining schools. The aim of the present study was to implement the 360-degree feedback in secondary school principals' performance. Data were collected from three principals, 32 secondary school teachers, and 181 male secondary school students in the Ninth District of Tehran, Iran using Armstrong's Questionnaire. The data analysis revealed the status of each principal in the first and second stages. The results of one-way analysis of variance (ANOVA) showed no statistically significant difference between the principals' self-evaluation results and those by the other groups (students and teachers) in the first stage. However, in the second stage, a statistically significant difference was found between the results of self-evaluation and evaluation by the other groups. Finally, the results demonstrated that providing feedback based on the 360-degree feedback paves the way for improving the performance of principals.