A just world belief is a belief that individuals develop that everyone finds what they deserve and that every person will receive a reward for every act they do, good or bad, that is, that the world is fair. The just world belief theory, which is like the consistency theories, was developed by Melvin Lerner in 1980. The theory of the just world belief emerged because of the realization of the tendency of people to legitimize injustice in the events they witness. Therefore, studies of the belief in a just world in the first two decades have generally focused on the tendency to justify injustice and humiliate the victim. Until the age of seven or eight, children believe in immanent justice and think that actions they deem wrong will be punished automatically. With adolescence, the immanent belief in justice turns into a belief in a just world. From this point on, the belief in a just world has two aspects: the personal belief in a just world and the general belief in a just world. Belief in the just world religion, environment, age, etc. has a relationship with the elements. In addition, adolescence is the period when a person's ideas about both justice and religion develop during the stages of life and are sensitive to these issues. There are few studies on just world beliefs in Turkey, and among these, there is no study on its direct relationship with religiosity. In this study, it is aimed to reveal the relationship between belief in a just world and religiosity during adolescence. In the study, the relationship between belief in a just world and religiosity was carried out with the participation of 428 high school students studying in five different high schools in the 2020-2021 academic year living in Gaziantep. In this context, adolescents' belief in a just world and its sub-dimensions, personal belief in a just world and general belief in a just world, were examined by using the questionnaire technique and the relational screening model. The data were analyzed using SPSS 19.0 statistical software. As a result of the research, significant relationships were found between the dimensions of religiosity and just world belief according to the results of correlation and regression analyses. When the relationship between the sub-dimensions of just world belief and religiosity was analyzed, it was found that personal just world belief and general just world belief had a weakly significant relationship with religiosity. Accordingly, with the increase in religiosity, an increase in the belief in a just world has been determined. When we look at the effect of the sub-dimensions of religiosity on the belief in a just world, it has been determined that the sub-dimensions of influence and worship have a positive effect on the belief in a just world, while the sub-dimensions of faith and emotion have no significant effect on the belief in a just world. As a result, when there is an increase in the dimensions of influence and worship, it has been seen that there is an increase in the belief in a just world. The most effective of these two is the effect size. * This study is derived from a master's thesis entitled "Just World Belief and Religiosity in Adolescents", completed by Muhammed Şahbaz in 2022 under the supervision of Assoc. Prof. Dr. Behlül Tokur (Ankara Yıldırım Beyazıt University, Institute of Social Sciences, Master's Thesis, 2022).