Internalization of peaceful Islamic culture in higher education is a concept that emphasizes the creation of a harmonious learning environment and respect for differences to achieve an effective, conducive, and minimally violent learning environment for students. Research on the internalization of Islamic culture of peace at the higher education level on the study of inner and social aspects to create peace often needs more attention. This study examines the effectiveness of Islamic inner and social peace culture in reducing student aggression in higher education. This research approach is quantitative research. The type of research is quasi-experimental non-equivalent control group design: the design used is pretest- posttest control group design. Respondents came from 3 universities in South Sulawesi, Indonesia. Forty-eight respondents were divided into two groups, experimental group (M=26.63, SD=3.41) and control group (M=24.38, SD=2.65) . Respondents in this study tended to have high levels of aggression. The sampling method used to collect data was purposive sampling. This research questionnaire uses a modified Buss-Perry Aggression Questionnaire (BPAQ) which has gone through a translation process using Indonesian with level reliability α= 0.763. The data analysis of this study used paired sample t-test. The results showed that the internalization of three principles in building an Islamic Culture of Inner and Social Peace, namely inner peace, soul cleansing, and noble morals, effectively reduced student aggression. This research implies that a harmonious learning environment in higher education can be achieved by strengthening the implementation of character building for students who are able to communicate, think critically, and solve problems peacefully.