This research was conducted at 15 government schools in Addis Ababa. The objectives of this research are to identify principal style and its effect on academic achievement. The “Leader Behaviour Description Questionnaire” (LBDQ) formed by Halpin (1966) was used. Meanwhile Academic achievement was measured using the “School Certificate Examination Results from 2017-2020. A total of 191 teachers and 15 principals from government school in Addis Ababa were randomly chosen. Pearson correlation was used to analyse the data. To support data obtained from questionnaire given 10 teachers were interviewed. The results showed that most of the school leaders adopt a democratic style of leadership. There was a significant correlation between the structure of task-oriented leadership style and students’ performance in the examinations. Correlation analysis also showed that principals practice task- oriented structure and consideration-oriented structure in relation to their work responsiblities. Furthermore, findings also showed that majority of the principals are more likely to practice consideration-oriented leadership style compared to structure-oriented leadership style.