This study aimed to identify the extent to which leadership with ethics is practiced by public school principals and its relationship to developing teachers’ performance in the South Al Sharqiyah Governorate in the Sultanate of Oman. The descriptive analytical correlational method and the questionnaire were used as a tool for collecting data for the study, which consisted of two parts: The first part is a scale consisting of (33) items to measure the extent of practicing ethical leadership among public school principals, and the second part is a scale consisting of (20) items to measure the level of teachers’ performance. The study sample chosen by the researcher in a simple random way consisted of (290) male and female teachers from Public schools in the South Al Sharqiyah Governorate, Oman . The results of the study showed the following: The extent of practicing leadership with ethics among government school principals in the South Al Sharqiyah Governorate was at a high level. The field of moral personal qualities ranked first and at a high level, the field of moral administrative qualities came in second place and at a high level as well, and the field of human relations ranked third at a high level. The results showed that there is a high level of developing teachers’ performance, and that there is a positive correlation between the extent to which public school principals practice ethical leadership and developing teachers’ performance, and showed that there are no statistically significant differences at the significance level (α≤0.05) depending on the demographic variables of the study sample members (Gender, Educational Qualification, and Years of Experience). Based on the results, the study recommends the following: - Work on developing various training programs and courses whose goal is to train government school leaders on ethical leadership in the South Al Sharqiyah Governorate in the Sultanate of Oman, to reinforce and maintain this high level of practice. -Enhancing this high level of practice of leadership with ethics among public school principals in the South Al Sharqiyah Governorate in the Sultanate of Oman. - Conduct more studies and research that examine the relationship between ethical leadership and variables other than those mentioned in this study . Keywords: leadership with ethics; Teacher performance; Developing teacher performance; South Sharqiyah Governorate.