The study examined community engagement in internal security for peace building in Rivers State. To achieve the purpose of the study, three (3) objectives, three (3) research questions and three (3) hypotheses guided the study. The study adopted descriptive design. The area of the study was Rivers State. The population of the study was made up of 46 Local Government Area Community Development Committee Chairmen (CDCC) and Local Government Area Divisional Police Officers (DPO). The entire population of this study was taken as census without sampling due to the manageable size of the population. The instrument for data collection was a self-developed questionnaire titled “Community Engagement in Internal Security for Peace Building Questionnaire”. The questionnaire was divided into two sections, A and B: Section A was used to gather demographic data of the respondents while section B elicited responses from respondents on the 15 questionnaire items drawn from the research questions of the study. The instrument was validated by two (2) experts from Faculty of Education, Rivers State University. A test of internal consistency using Cronbach Alpha method was used for the reliability of the instrument. Cumulative reliability coefficient of 0.82 was obtained. The research questions were answered using mean and standard deviation while the null hypotheses were tested using z-test statistics at 0.05 level of significance. The study among others revealed that community engagement in collaboration with community policing, security sensitization programmes and justice practice enhanced peace building in Rivers State to a high extent. Based on the findings, the study recommended among others that the community authorities/leaders should collaborate with external security agents like the police by reporting crimes to the nearest police station, initiating and training vigilante operatives for peace building.