The development and enhancement of the principal’s job performance is considered the key objective sought by education, and the way leading to the strength of education. The research problem is represented in the decrease of academic achievement levels at some schools of the Sultanate, as well as their levels in the local and international activities and contests. Therefore, this study aims to investigate the relation between the basic education schools principal’s possession of metacognitive thinking and the job performance in the Sultanate of Oman. The study also aims to identify the principals’ metacognition level, as well as the difference of its level with the difference of the variables of gender, qualification, and years of experience. Therefore, the research adopts the blended approach that combines the analytical descriptive approach and the qualitative approach. Furthermore, the research has employed three instruments. The first instrument is represented in Schraw and Dennison Scale to measure the level of metacognitive thinking; the second is the job performance questionnaire, where its validity and reliability has been measured for all axes. While the third instrument includes the interviews with the administrative supervisors. The research population consisted of all the basic education schools’ principals affiliated to the Ministry of Education in the Sultanate of Oman for the school year (2020/2021), totaling 779 male and female principals in all the governorates of the Sultanate, i.e., 11 governorates. While the research sample included 260 male and female principals in accordance with Krejcie & Morgan Table from all governorates, in order to be able to generalize the research findings appropriately, and they were selected based on the simple random sampling method. While the second sample was the administrative supervisors sample totaling 10 administrative supervisors to conduct the interviews with them, and they were selected from all governorates. The researcher also adopted the (SPSS) program in the statistical analysis process, which suits the nature of study, including arithmetical averages and standard deviations, factor analysis, analysis of variance (ANOVA), multivariate analysis of variance (MANOVA), correlation test and the interview content analysis. The research concluded that there is a strong positive and significant relation at the level of (0.05) for the metacognitive thinking in its three dimensions- knowledge organization, learning knowledge and knowledge processing on the job performance skills- planning, control and orientation, and evaluation. Moreover, the results revealed that there is a positive relation between the metacognitive thinking (in whole) and the job performance skills (planning, control and orientation, and evaluation); and that the learning knowledge dimension was the highest dimension possessed by the principals of basic education schools. In addition, the researcher recommends that further studies should be conducted in this field, such as the effectiveness of a program for metacognitive thinking in the areas of management and education.