Prison are places to carry out the coaching process for convicts in isolated areas as a form of imposing criminal sanctions for violations of the law. Not all rights of convicts are eliminated, one of the fulfillment of rights that can still be given is the fulfillment of the right to worship as recommended by the 1945 Constitution articles 28 and 29 concerning respect for the right to freedom of worship, so that further granting the right to worship is based on law number 22 of 2022 concerning institutions penitentiary which regulates the implementation procedures and recommendations. The increasing number of convicts has resulted in various problems in the field of religious development. The purpose of this research is to analyze the legal basis and its implementation towards fulfilling the right to freedom of worship in Class 1 prisons in Surabaya. The research method uses an empirical legal approach with a qualitative research type, the process of collecting data by means of observation, interviews and documentation is then analyzed in relation to the application of the applicable legal basis in the field which is presented in narrative form as a conclusion. The results of the study concluded that the implementation of fulfilling the right to freedom of worship which is manifested in the process of spiritual development is in accordance with the applicable legal basis, but several obstacles such as the lack of enthusiasm from the prisoners themselves about the importance of activities still need to be improved through socialization.