This research aims to answer how the implementation of religious character education building based on school culture and conducted a successful program at SMAN 5 Yogyakarta (Yogyakarta 5 Public High School). This study is highly important to conduct since the religious character is an essential value in the learning process in Indonesia. The research subjects consisted of school principals, teachers, and students. Determination of the subjects carried out by purposive sampling. Data collection used interview, observation, and documentation. An interactively inductive data analysis technique performed data analysis with data reduction stages, data displays, and conclusion drawing. The results of the study showed that: 1) the implementation of religious character education building based on school culture was carried out through character building based on religious values, school climate based on religious values, extracurricular activities based on religious values, as well as building relationships between schools and the societies. 2) The impact of the strengthening program of character education produces two themes as follows: the growth of students' religious awareness and the growth of tolerance among religious communities. The findings of this study indicated the importance of the school's cultural base in implementing holistic religious character education programs in schools. This finding also strengthens the previous research findings, which had mentioned that the religious character is an essential character for students in a secondary school in Indonesia, and also strengthen that Indonesia's society, in general, is religious people.